(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Report of the British Association for the Advancement of Science"

V ' 



ry 



(I 




yS: /.Ail 



REPORT 



OF THE 



BRITISH ASSOCIATION 



FOR THE ADVANCEMENT OF SCIENCE 




1918. 



/■■' 



LONDON 
JOHN MURRAY, ALBEMARLE STREET 

1919 

Office, of the Association: Burlington House, London, W.i. 



PREFACE. 

The Annual Meeting of the British Association in 1918 was can- 
celled, for the second year in succession, under circumstances described 
in the Report of the Council included in this volume. 

As in 1917, the Organising Committees of the Sections, having been 
empowered by the Council to do so, held in the early part of the summer 
such meetings as were necessary to transact such business as was essen- 
tial in spite of the cancellation of the Annual Meeting, including the 
forwarding to the Committee of Recommendations of proposals fm 
the appointment or reappointment of Research Committees, and for 
grants of money to some of them. The Organising Committees were 
also empowered to receive Reports from Research Committees, and to 
recommend for printing in the Annual Report such of these Reports 
as it was thought undesirable to delay. 

On July 5, 1918, in the rooms of the Linnean Society, meetings 
were held of: — 

The Council, at 11.30 a.m., to approve the Report of the 
Council to the General Committee, and for other business ; 

The General Committee, at 12 noon, to receive the Reports 
of the Council and of the General Treasurer, to confirm the 
arrangements made in connection with the cancellation of the 
Annual Meeting, and for other business; 

The Committee of Recommendations, at 2.30 p.m., to make 
recommendations to the General Committee concerning the appoint- 
ment of, and grants of money to. Research Committees, etc. ; 

The General Committee, at 4 p.m., to receive the Report of the 
Committee of Recommendations. 

The present volume contains, as usual, the Reports of the Council 
and of the General Treasurer, and the list of Research Committees 
appointed by the General Committee. The usual lists and other 
records referring to previous meetings are omitted. For the rest, 
the volume contains only the Reports of Research Committees, referred 
to above, of which the General Committee, on the advice of the other 
committees concerned, decided that it would be undesirable to delay 
the issue. The Report of the Meeting of the Conference of Delegate.? 
of Corresponding Societies, which was held in the rooms of the Geo- 
logical Society on July 4, is also included. 



1918. 



CONTENTS. 



m 

PAGE 

Officbbs and Council, 1018-19 iv 

Eepoet of the Council to the General Committee, 1917-18 vi 

General Treasurer's Account, 1917-18 viii 

Research Committees x 

Research Committees 'in Suspense' xviii 

Synopsis of Grants of Money xix 

Reports on the State of Science, etc. 
Report of Committee on Seismological Investigations 3 

Preliminary Report on Tides and Tidal Currents. By H. Lamb and 
J. Proudman 15 

Report of Committee on Impact Tests 17 

Report of Committee on Archaeological Investigations in Malta ... 42 

Report of Committee on Exploration of the Palseolithic Site known as 
La Cotte de St. Brelade, Jersey 42 

Report of Committee on the ' Free-Place ' System 48 

Report of Committee on Plant Pathology 56 

Report of the Corresponding Societies Committee and of the Conference 
of Delegates of Corresponding Societies 59 

Presidential Address by Dr. F. A. Bather, F.R.S., on the 
Contribution of Local Societies to Adult Education 60 

Kent's Cavern 68 

Afforestation : Its Practice and Science. By M. C. Duchesne... 68 

Note on Typomap made by Mr. B. B. Woodward 79 

List of Corresponding Societies 85 

Catalogue of Papers 90 

Second Report of Committee on Colloid Chemistry and its Industrial 
Applications 1-172 

List of Publications 14 

a2 



OFFICERS AND COUNCIL, 1918-19. 



PATRON. 
HIS MAJESTY THE KING. 

PRESIDENT. 
Sm ABTHUB EVANS, D.Litt., LL.D., Pres.S.A., F.B.6. 

PRESIDENT ELECT. 
The Hon. Sir Oham.es A. Parsons, K.O.B., ScD., F.B.S. 

GENERAL TREASURER. 
Profeasor John Perrt, D.Sc, LL.D., P.K.S., Burlingtou House, IjondoD, W. 1. 

GENERAL SECRETARIES, 
Pr^eseor W. A, Herdman, D.Sc, LL.D., F.R.S. | Profeasor H. H. Tdrnbb, D.Sc, D.O.L., F.H.S. 

ASSISTANT SECRETARY. 
0. J. R. HOWARTH, M.A., Burlington House, London, W. 1. 

CHIEF CLERK AND ASSISTANT TREASURER. 
H. 0. Stewaboson, Burlington House, London, W. 1. 



ORDINARY MEMBERS OF THE COUNCIL. 



Armstrong, Dr. E. P. 

Bone, Professor W. A., F.R.S. 

Brabrook, Sir Edward, C.B. 

Olerk, Sir DUGALD, K.B.E., F.R.S. 

Dkndy, Professor A., F.R.S. 

Dickson, Professor H. N., O.B.E., D.Sc 

DlXET, Dr. F. A., F.R.S. 

Dyson, Sir F. W., F.R.S. 

Gregory, Sir R. A. 

Halliburton, Professor W. D., F.R.S. 

Harxer, Dr. S. F., F.R.S. 

IH Thdrn, Sir E. F., K.O.M.G. 

Jeans, Professor J. H., F.R.S. 



Keith, Professor A., F.R.S. 
MoRKis, Sir D., K.O.M.G. 
Perkin, Professor W. H., F.R.S. 
Russell, Dr. E. J , O.B.E., F.B.S. 
Ruthkrford, Sir E., F.R.S. 
Saunders, Miss B. R. 
Scott, Professor W. R. 
Starling, Professor E. H., F.R.S. 
SiRAHAN, Sir A., F.R.S. 
Weiss, Profe.ssor F. E., F.R.S. 
Whitaker, W., F.R.S. 
Woodward, Dr. A. Smith, F.R.S. 



EX-OFFICIO MEMBERS OF THE COUNCIL. 

The Tmateea, past Presidents of the Association, the President and Vice-Presidents for the year, tb« 
President and Vice-Presidents Elect, past and present General Treasurers and General Secretaries, past 
Assistant General Secretaries, and the Local Treasurers and Local Secretaries for the ensuing Annual 

Meeting 



TRUSTEES (PERMANENT). 

The Bight Hon. Lord Ratleigh, CM., M»A.., D.O.L., LL.D., V.BS., I'.B^.S. 
Major P. A. MacMabon, D.Sc, LL.D., F.R.S., F.B.A.S. 



OFFICERS AND COUNCIL. 



PAST PRESIDENTS OP THE ASSOCIATION. 



Lord Rayleigh, O.M., F.R.S. 

Sir A. Oelkie.K.O.B., O.M., F.R.S. 

Sir James Dewar, F.R.S. 

Sir NormanLookyer,K.O.B.,F.R.S. 

Arthur J. Bklfoor, O.M., F.R.S. 



Sir E.Bay Lankester,K.O.B.,F.R.S. I Sir B. Sbarpey Sohafer, P.R.S. 
Sir Francis Darwin, F.R.S. Sir Oliver Lodge, F.R.S^ 

Sir J. J. Thom8on,O.M., Pres.R.S. 
Professor T. Q. Bonney, F.R.S. 



Professor W. Bateson, P.B.S. 
Professor A. Schneter, F.B;.8. 



PAST GENERAL OFFIOBBS OP THE ASSOCIATION. 



Professor T. Q. Bonney, F.R.S. 
Dr. A. Vernon Harcoart,FJl.S. 



I Sir E. Sharpey Sohafer, P.R.S. 
1 Dr. D. H. Scott, F.R.S. 



I Dr. J. G. Garson. 

I Major P. A, UaoMahon, F.R.S. 



Sir Edward Brebrook, C.B. 



AUDITORS. 

I Sir Ererard im Thurn, C.B., K.O.M.6. 



VI REPORT OF THE COUNCIL. 

REPOET OF THE COUNCIL, 1917-18. 

I. At their meeting in March the Council received the following 
resolution from the Local Executive Committee at Cardiff: — 

" That having fully considered the question of the visit of the British 
Association to Cardiff this year, the Committee is of opinion 
that under existing circumstances it is desirable to postpone 
the visit to the first opportunity after the war. The Com- 
mittee is deeply disappointed that circumstances over which 
it has no control make this course advisable, but it is of opinion 
that the visit could not, during the war, be carried out in such 
a manner as the City and district would desire." 

The Council adopted the following resolution : — 
" The Council of the British Association have considered the resolu- 
tion of the Local Executive Committee at Cardiff, in which the 
opinion is expressed that it is desirable to postpone the visit of 
the Association to Cardiff. The Council sincerely regret the 
necessity for this decision, but under the circumstances fully 
concur in it, and it is, therefore, resolved that the Meeting at 
Cardiff be postponed." 

The following resolution was subsequently passed by the Parlia- 
mentary Committee and confirmed by the City Council of Cardiff, and is 
referred to the General Committee : — 

" That in order to comply with the formalities of the Association, 
this Committee recommend the Council cordially to renew the 
invitation (formally presented on the 7th September, 1916, by 
an influential deputation) to the British Association to visit 
Cardiff' in one of the following years, namely: — 1919, 1920, or 
1921, having regard to the unavoidable postponement of the 
visit this year, such renewed invitation to be made by letter in 
accordance with the suggestion received." 

The Council desire to place on record their grateful appreciation of 
the cordial co-operation of the authorities at Cardiff in the discussions 
which have taken place. 

II. The Council discussed the question of holding a Meeting of the 
Association or a General Conference in London during the present year, 
but proposals to such effect were withdrawn. 

Having regard to the cancellation of the Annual Meeting, the Council 
have made arrangements similar to those which obtained last year for 
carrying on the necessary business of the Association. 

III. The Council recommend that Sir Arthur Evans' term of office as 
President be extended until the beginning of the next Annual Meeting. 

IV. The Association has received from the Royal Society a grant of 
250Z. for purposes of research and publication during the current year, 
and the Council returned to the Society a most cordial vote of thanks on 
behalf of the Association. 

V. A grant of Ql. from the interest of the Caird Fund was made to 
the Committee appointed to arrange meetings, &e., on Geophysical 
subjects. 



REPORT OF THE COUNCIL. VU 

VI. The Council propose to the General Committee the following 
addition to the Rules : — 

In Rule 1, Chap. X., following the words ". . . to cancel a ticket 
of admission already issued," 

" If it appears to the Council that it is not desirable that a person 
shall continue to be a Member or Associate of the Association, the Council 
shall direct the General Secretaries to ascertain whether that person is 
willing to resign his membership or associateship. 

" If that person do not, within a time to be fixed by the Council, either 
resign or appeal in writing to the General Committee, the Council may 
declare him to be no longer a Member or Associate. Upon the appeal, 
the General Committee may make the like declaration by a majority of 
two-thirds of those present and voting. 

" The Council shall also have power to refuse application for member- 
ship or associateship." 

VII. The Council have received accounts from the General Treasurer 
during the past year, and these will be presented to the General Com- 
mittee subject to audit. 

VIII. The Council recommend to the General Committee that, in 
view of the diminution of business consequent upon the cancellation of 
the Annual Meeting, there be no change this year in the personnel of the 
Ordinary Members of Council, and that the operation of Rules 1 and 3, 
Chap, v., governing such change, be suspended. 

In consequence of this recommendation, the Council do not notify the 
names of any of its members for retirement, and have made no nomi- 
nations of new members. 

IX. The General Officers have been nominated by the Council as 
follows : — 

General Treasurer : Prof. J. Perry. 
General Secretaries : Prof. W. A. Herdman. 
Prof. H. H. Turner. 

X. Conference of Delegates and Corkespondino Societies 
Committee : — 

The following appointments have been made by the Council : — 

Conference of Delegates. — Dr. F. A. Bather {President), Mr. Mark L, 
Sykes {Vice-President), Mr. W. Mark Webb {Secretary). 

Corresponding Societies Committee. — Mr. W. Whitaker {Chairman), 
Mr. W. Mark Webb {Secretary), Dr. F. A. Bather, Rev. J. O. Bevan, Sir 
Edward Brabrook, Sir H. G. Fordham, Mr. J. Hopkinson, Mr. A. L. 
Lewis, Mr. T. Sheppard, Rev. T. E. R. Stebbing, Mr. Mark L. Sykes, 
and the President and General Officers of the Association. 

The Council approved a proposal from the Committee that a 
Conference of Delegates should be held in London on or about July 4, 
and they therefore made the appointments above mentioned as a matter 
of urgency. 



fill 



GENERAL TREASURER S ACCOUNT. 



Dr. THE GENERAL TREASURER IN ACCOUNT 

ADVANCEMENT OF SCIENCE, 

RECEIPTS. 

£ s. d. £ s. (/. £ i. (1. 
To Balance brought forward : - 

Lloyds Bank, Birmingham 1,822 14 2 

Williams Deacon's Bank, Manchester 421 11 5 

Barclay & Co.. Newcastle 281 4 

Bank of England — Western Branch : — 

On ' Caird Fund ' 317 11 4 

i?sj General Account overdrawn 179 13 10 

137 17 6 

2,663 3 5 

ZMi Petty Cash overdrawn 2 15 11 

2,660 7 6 

Life Compositions (including Transfers) 67 

Annual Subscriptions 532 

New Annual Members' Subscriptions 4 

Sale of Associates' Tickets 1 

Sale of Publications 217 13 11 

Grants from Royal Society:— 

In aid of Publication Expenses 150 

For purposes of Research 100 

250 

Donations 8 7 

Interest on Deposits : — 

Barclay & Co., Newcastle 2 9 2 

Williams Deacon's Bank, Manchester 6 11 11 

Lloyds Bank, Birmingham 20 9 9 

„ „ 'OairdFund' 34 3 

63 13 10 

Unexpended Balances of Grants rcturnal 49 2 

Dividends on Investments: — 

Consols 2J per Cent 87 4 4 

India 3 per Cent 81 

Great Indian Peninsula Railway ' B ' Annuity 24 6 9 

War Stock 5 per Cent 43 3 

War Bonds 5 per Cent 50 15 

286 9 1 

Dividends on ' Caird Fund ' Investments :— 

India 3J per Cent 68 19 

Canada 34 per Cent, (including extra J per Cent.) 75 

London and South- Western Railway ConsoUdated4 per (jeut. Preference 

Stock 75 

London and North- Western Railway Consolidated 4 per Cent. Preference 

Stock 63 

281 19 U 



Nominal 
£ 

4,651 
3,600 
879 
2,627 
2,100 

2,500 

2,500 

93 

863 
1,400 
1,000 



Amount, 
s. d. 
10 


14 9 

10 





Investments. 







1) 



Consolidated '21, per Cent. Stock 

India 3 per Cent. Stock 

(Nominal) Great Indian Peninsula Railway £43 'B' Annuity 

India 3J per Cent. Stock, ' Caird Fund ' 

London and North- Western Railway Consolidated 4 per Cent. 

Preference Stock, 'Caiid Fund' 
Canada 3J per Cent. (1930-50) Registered Stock, deposited with 

Treasury, ' Caird Fund ' 
London and South- Western Railway Consolidated 4 per Cent. 

Preference Stock, 'Caird Fund' 
Sir Frederick Bramwell's Gift of ^ per Cent. Self-Cumulating 

Consolidated Stock 
War Loan 5 per Cent. Stock 
War Bonds 5 per Cent., 1929-47 
Lloyds Bank, Birmingliam — Deposit Account included in Balance 

.It Bank, Sir J. Caird's Gift for Radio-Activity Investigation 



£22,214 13 3 



£4,421 12 4 



Value at 30th June, 1918, £15,335 is. lOiJ. only. 



GENERAL TREASURER S ACCOUNT. IX 



WITH THE BRITISH ASSOCIATION FOR THE Cr. 

July 1, 1917, to June 30, 1918. 

PAYMENT=i. 

£ s. d. 

By Rent and Office Expenses 85 7 8 

Salaries.etc 6T8 

Printing, Binding, etc 1,028 10 2 

Grants to Research Committees : — £ s. d. 

Seismological Observations 100 

Colloid Ciiemistry and its Industrial Applications 10 

Old Red Sandstone Rocks of Kiltorcan 5 

Inheritance in Silkworms 3 

Women In Industry 10 

„ „ 1917 10 11 

Effects of the War on Credit, etc 10 

„ 1917 10 

Archseological Investigations in Malta 10 

Distribution of Bronze Age Implements 18 U 

Artificial Islands in Highland Lochs 2 10 

Physiology of Heredity 15 

The ' Free Place ' System 5 

Science Teaching in Secondary Schools 4 3 10 

Corresponding Societies Committee 26 

220 IS 3 

Grants made from ' Caird Fund ' 106 

Balanceat Lloyds Bank, Birmingham (with Interest accrued), including 
Sir James Oaird's Gift, Radio-Activity Investigation, of £1,000 and 

Interest accrued thereon £139 Is. Sd.... 1,877 B 11 

Balance at Bank of England— Western Branch :— 

On 'Caird Fund" £493 10 4 

Z<M General Account overdrawn 68 4 10 

425 5 (; 



Cash in hand 1 111 

Z<M Petty Cash overdrawn .. 13 1 



John Pbbry, General Treasurer. 



2,302 12 5 
8 10 



£4,421 12 4 



I have examined the above Account with the Books and Vouchers of the Association, and certify the 
same to be correct. I have also verified the Balances at the Bankers, and have ascertained that the Invest- 
ments are registered in the names of the Trustees, or hold by the Bank of Engiand on account of the 
Association. 

W. B. Eeex, Chartered Aeeountnnt. 
Approvrd — Octobff 8, 1918. 

Edward Brabrook, i . ... ,., 

EVEBARD lU THnRN-, \ •*'"«'»"'• 



RESEARCH COMMITTEES. 



LIST OF GRANTS, 1918. 



Research Committees, etc., appointed by the General Committee, 

MEETING IN LoNDON : JuLY, 1918. 



1. Receiving Grants of Money. 



Subject for Investigation, or Purpose 



Members of Committee 



Section A.— MATHEMATICS AND PHYSICS. 

Seismological Investigations. 1 Chairman. — ProfessorH. H.Turner. 

Secretary. — Mr. J. J. Shaw. 

Mr. C. Vernon Boys, Dr. J. E. 

; Crombie, Mr. Horace Darwin, 

I Dr. C. Davison, Sir F. W. Dyson, 

Sir E. T. Glazebrook, Professors 

C. G. Knott and H. Lamb, Sir J. 

I Larmor, Professors A. E. H. 

I Love, H. M. Macdonald, J. Perry, 

and H. C. Plummer, Mr. W. E. 

Plummer, Professors E. A. 

I Sampson and A. Schuster, Sir 

Napier Shaw, Dr. G. T. Walker, 

and Mr. G. W. Walker. 



To arrange meetings in the ensu- 
ing year for the discussion of 
papers and reports on Geophy- 
sical subjects, and to co-operate 
with existing Committees in 
making recommendations for 
the promotion of the study of 
such subjects in the British 
Empire. 



Chairman.— ^\x F. W. Dyson. 

Secretary. — Dr. S. Chapman. 

Dr. C. Chree, Sir Charles F. Close, 
Mr. J.H. Jeans.Professor A. B. H. 
Love, Major H. G. Lyons, Pro- 
fessors H. F. Newall and A. 
Schuster, Sir Napier Shaw, Sir 
A. Strahan, Professor H. H. 
Turner, and Dr. G. W. Walker. 



Colloid Chemistry and its In 
dustrial Applications. 



Section B.— CHEMISTRY. 

Professor 



F. G. 



Research on Non-Aromatic Dia- 
zoninm Salts. 



-Professor W. C. McC. 



Chairman. 
Donnan. 

Secretary .- 
Lewis. 

Dr. B. F. Armstrong, Professor 
A. J. Brown, Dr. C. H. Desch, 
Mr. E. Hatschek, Professors 
H. E. Procter and W. Ramsden, 
Mr. A. S. Shorter, Dr. H. V. 
Stevens, and Mr. H. B. Stocks. 

Chairman. — Dr. F. D. Chattaway. 
Secretary. — Professor G. T. Morgan 
Mr. P. G. W. Bayly and Dr. N. V. 
Sidgwick. 



Section D.— ZOOLOGY. 



Experiments in Inheritance in 
Silkworms. 



Chairman. — Professor W. Bateson. 
Secretary. — Mrs. Merritt Hawkes. 
Dr. F. A. Dixey and Dr. L. Don- 
caster. 



Grants 



£ 
100 



i. d. 





10 



5 



17 



RESEARCH COMMITTEES. 
1. Receiving GraMs of Money — continued. 



XI 



Subject for Inyestigation, or Purpose 




Section F.— ECONOMIC SCIENCE AND STATISTICS. 



Replacement of Men by Women 
in Industry. 



The EflEects of the War on Credit, 
Currency, and Finance. 



(7A<iir»ta«.— Professor W. R. Scott. 

Sveretary.—Wi?,?, Grier. 

Miss Ashley, Ven. Archdeacon 
Cunningham, Professor E. C. K. 
Gonner, Mr. J. E. Highton, 
and Professor A. W. Kirkaldy. 

<7/tairm««.— Professor W. R. Scott. 

Secretary. — Mr. J. E. Allen. 

Professor C. F. Bastable, Sir E. 
Brabrook. Professor Dicksee, 
Mr. B. Ellinger, Mr. A. H. 
Gibson, Professor E. C. K. 
Gonner, Mr. F. W. Hirst, Pro- 
fessor A. W. Kirkaldy, and Mr. 
E. Sykes. 



Section H.— ANTHROPOLOGY. 



To excavate a Palaeolithic Site in 
Jersey. 



To conduct Archasological Inves- 
tigations in Malta. 



To report on the Distribution of 
Bronze Age Implements. 



The Collection, Preservation, and 
Systematic Registration of Pho- 
tographs of Anthropological 
Interest. 



[To conduct Explorations with the 
object of ascertaining the Age 
of Stone Circles. 

(^Committee in suspense: grant for 
contingent Uahility.) 



Chairman. — Dr. R. R. Marett. 

Secretary. — Mr. G. de Gruchy. 

Dr. C. W. Andrews, Mr. H. Bal- 
four, Professor A. Keith, and 
Colonel Warton. 

Chairman.— FvotessoT 3 . L. Myres. 
Secretary. — Dr. T. Ashby. 
Mr. H. Balfour, Dr. A. C. Haddon, 
and Dr. R. R. Marett. 

Chainnan. — Professor J. L. Myres. 

Secretary. — Mr. H. Peake. 

Professor W. Ridgeway, Mr. H. 
Balfour, Sir C. H. Read, Pro- 
fessor W. Boyd Dawkins, Dr. 
R. R. Marett, and Mr. 0. G. S. 
Crawford. 

C]iairman.—^\T C. H. Read. 

Secretary. — Dr. Harrison. 

Dr. G. A. Auden, Dr. H. O. Forbes, 

Mr. E. Heawood, and Professor 

J. L. Myres. 

Chairman. — Sir C. H. Read. 

Secretary. — Mr. H. Balfour. 

Dr. G. A. Auden, Professor W. 
Ridgeway, Dr. J. G, Garson, Sir 
Arthur Evans, Dr. R. Munro, 
Professors Boyd Dawkins and 
J. L. Myres, Mr. A. L. Lewis, 
and Mr. H. Peake.] 



£ 

10 



s.d. 




10 







10 



10 



1 



15 



Xll 



RESEARCH COMMITTEES. 
1. Receiving Grants of Money— conimuedi. 



Subject for Investigation, or Purpose 



Members of Committee 



Grants 



Section I.— PHYSIOLOGY. 



The Ductless Grlands. 



Chairman. — Sir E. S. Schafer. 

Secretary. — Professor Swale Vin- 
cent. 

Dr. A. T. Cameron and Professor 
A. B. Macallnm. 



Section K.— BOTANY. 



Experimental Studies in 
Physiology of Heredity. 



the I Chairman. — Dr. F. F. Blackman, 
Secretary. — Mr. R. P. Gregory. 
Professors Bateson and Eeeble 
and Miss E. R. Saunders. 



To cut Sections of Australian 
Fossil Plants, with especial re- 
ference to a specimen of Zygo- 
pteris from Simpson's Station, 
Barraba, N.S.W. 

The Collection and Investigation 
of Material of Australian Cyca- 
dacese, especially Bowenia from 
Queensland and Macrozamia 
from West Australia. 



Cliairvian. — Professor Lang. 
Secretary. — Professor T. G. B. 

Osborn. 
Professors T. W. Edgeworth David 

and A. C. Seward. 

Chairman. — Professor A. A. Law- 
son. 

Secretary. — Professor T. G. B. 
Osborn. 

Professor A. C. Seward. 



Section L.— EDUCATIONAL SCIENCE. 



The Effects of the 'Free-place' 
System upon Secondary Educa- 
tion. 



Chairman. — Mr. C. A. Buckmaster. 

Secretary. — Mr. D. Berridge. 

Mr. C. H. Bothamley, Miss L. J. 
Clarke, Miss B. Foxley, Dr. W. 
Garnett, Professor R. A. 
Gregory, Mr. J. L. Paton, 
Professor H. Bompas Smith, 
Dr. H. Lloyd Snape, and Miss 
Walter. 



CORRESPONDING SOCIETIES. 



Corresponding Societies Com- 
mittee for the preparation of 
their Report. 



Chairman. — Mr. W. Whitaker. 

Secretary. — Mr. W. Mark Webb. 

Dr. F. A. Bather, Rev. J. O. 
Bevan, Sir Edward Brabrook, 
Sir H. G. Fordham, Mr. J. 
Hopkinson, Mr. A. L. Lewis, 
Mr. T. Sheppard. Rev. T. R. R. 
Stebbing, Mr. Mark L. Sykes, 
and the President and General 
OfBcers of the Association. 



a. d. 




15 



15 



7 17 



5 







RESEARCH COMMITTEES. 
2. Not receiving Orants of Money.* 



uu 



Subject for InvestigatioD, or Purpose 



Members of Committoe 



Section A.— MATHEMATICS AND PHYSICS. 

Annual Tables of Constants and Nu- Chairman. — Sir E. Rutherford. 



merical Data, chemical, physical, and 
technological. 

Calculation of Mathematical Tables. 



Investigation of the Upper Atmosphere. 



Badiotelegiaphic Investigations. 



Determination of Gravity at Sea. 



To aid the work of Establishing a Solai- 
Observatory in Australia. 



To discnss the present needs of Geodesy, 
including its relation to other 
branches of Geophysics, and to report 
to the next meeting of the British 
Association, with power to present 
an interim report to the Council if 
any question of urgency should 
arise.f 



Secretary. — Dr. W. C. McC. Lewis. 

Chairman. — Professor M. J. M. Hill. 

Secretary. -Vvoiessox J. W. Nicholson. 

Dr. J. R. Airey, Mr. T. W. Chaundy, Pro- 
fessor L. N. G. Filon, Sir G. Greenhill, 
Professor E. W. Hobson, Mr. G. 
Kennedy, and Professors Alfred 
Lodge, A. E. H. Love, H. M. Mac- 
donald, G. B. Mathews, G. N. Watson, 
and A. G. Webster. 

Chaifmian. — Sir Napier Shaw. 

Secretary. — 

Mr. C. J. P. Cave, Mr. W. H, Dines, Sir 
E. T. Glazebrook, Sir J. Larmor, 
Professors J. E. Petavel and A. 
Schuster, and Dr. W. Watson. 

Chairnian. — Sir Oliver Lodge. 

Secretary. — Dr. W. H. Eccles. 

Mr. S. G". Brown, Dr. C. Chree, Sir F. W, 
Dyson, Professor A. S. Eddington, Dr, 
Erskine-Murray, Professors J. A. Flem 
ing, G. W. O. Howe, H. M. Macdonald 
and J. W. Nicholson, Sir H. Norman 
Captain H. R. Sankey, Professor A 
Schuster, Sir Napier Shaw, and Pro 
fessor H. H. Turner. 

Chairman. — Professor A. E. H. Love. 

Secretary.— Bt. W. G. Duffield. 

Mr. T. W. Chaundy and Professors A. S. 

Eddington, A. Schuster, and H. H. 

Turner. 

Chairman. — Professor H. H. Turnec. 

Secretary. — Dr. W. G. Duffield. 

Rev. A. L. Cortie, Dr. W. J. S. Lockyer, 

Mr. F. McClean, and Professor A. 

Schuster. 

Chairman. — Colonel Sir C. F. Close. 

Secretary. — Colonel E. H. Hills. 

Sir S. G. Burrard, Dr. W. G. Duffield, 
Mr. Horace Darwin, Sir F. W. Dyson, 
Sir R. T. Glazebrook, Mr. A. R. 
Hinks, Sir T. H. Holdich, Professor 
Lamb, Sir Joseph Larmor, Professor 
A. B. H. Love, Colonel H. G, Lyons, 
Professor H. Macdonald, Mr. R. D. 
Oldham, Professor A. Schuster, Sir 
Napier Shaw, Professor H. H. Turner, 
and Dr. G. W. Walker. 

• Excepting the case of Oomtuittees receiving grants from the ' Oaird Fuud.' . 
t Joint Committee with Section E. Empowered to report to Council. 



XIY 



RESEARCH COMMITTEES. 
2. Not receiving Grants of Money — continued. 



Subject or Investigation, or Purpose 



Members of Committee 



Section B.— CHEMISTRY. 



Fuel Economy ; Utilisation of Coal ; 
Smoke Prevention. 



Absorption Spectra and Chemical Con- 
stitution of Organic Compounds. 



Ghairmmi. — Mr. Robert Mond. 

Secretary. — 

The Rt. Hon. Lord AUerton, Mr. Robert 
Armitage, Professor J. O. Arnold, Mr. 
J. A. F. Aspinall, Mr. A. H. Barker, 
Professor P. P. Bedson, Sir G. T. 
Beilby, Sir Hugh Bell, Professor W. S. 
Boulton, Professor E. Bury, Dr. Charles 
Carpenter, Sir Dugald Clerk, Pro- 
fessor H. B. Dixon, Dr. J. T. Dunn, 
Mr. S. Z. de Ferranti, Dr. Wilham 
Galloway, Professors W. W. Haldane 
Gee and Thos. Gray, Mr. T. Y. 
Greener, Sir Robert Hadfield, Dr. H. S. 
Hele-Shaw, Dr. D. H. Helps, Dr. G. 
Hickling, Mr. Grevil Jones, Mr. W. W. 
Lackie, Mr. Michael Longridge, Dr. 
J. W. Mellor, Mr. C. H. Merz, Mr. 
Bernard Moore, Hon. Sir Charles 
Parsons, Sir Richard Redmayne, Pro- 
fessors Ripper and L. T. O'Shea, Mr. 
R. P. Sloan, Dr. J. E. Stead, Dr. A. 
Strahan, Mr. C. E. Stromeyer, Mr. 
Benjamin Talbot, Professor R. Threl- 
fal), Mr. G. Blake Walker, Dr. R. V. 
Wheeler, Mr. B. W. Winder, Mr. W. B. 
Woodhouse, Professor W. P. Wynne, 
and Mr. H. James Yates. 

Chairman. — Sir J. J. Dobbie. 
Secretary. — Professor E. E. C. Baly. 
Mr. A. W. Stewart. 



Section C— GEOLOGY. 



To investigate the Geology of Coal- 
Seams. 



The Old Red Sandstone Rocks of 
Kiltorcan, Ireland. 



To investigate the Flora of Lower Car- 
boniferous times as exemplified at a 
newly-discovered locality at GuUane, 
Haddingtonshire. 



Chairman. — Professor W. S. Boulton. 

Secretan-y. — Dr. W, T. Gordon. 

Mr. G. Barrow, Professors Sir John 
Cadman, Grenville Cole, and W. G. 
Fearnsides, Dr. J. S. Flett, Dr. Walcot 
Gibson, Professors J. W. Gregory and 
P. F. Kendall, Dr. R. Kidston, Profes- 
sor T. F. Sibly, Dr. A. Strahan, and 
Mr. J. R. R. Wilson. 

Chairman. — Professor Grenville Cole. 
Secretary. — Professor T. Johnson. 
Dr. J. W. Evans, Dr. R. Kidston, and 
Dr. A. Smith Woodward. 

Chairman. — Dr. R. Kidston. 
Secretary. — Dr. W. T. Gordon. 
Dr. J. S. Flett, Professor E. J. Garwood, 
Dr. J. Home, and Dr. B. N. Peach. 



RESEARCH COMMITTEES. 
2. Not receiving Grants of Money — continued. 



XV 



Subject for Investigation, or Purpose 



To excavate Critical Sections in the 
Palasozoic Rocks of England and 
Wales. 



To excavate Critical Sections in Old 
Red Sandstone Rocks at Rhynie, 
Aberdeenshire. 



To consider the Nomenclature of the 
Carboniferous, Permo-carboniferous, 
and Permian Rocks of the Southern 
Hemisphere. 



To consider the preparation of a List 
of Characteristic Fossils. 



The Collection, Preservation, and Sys- 
tematic Registration of Photographs 
of Geological Interest. 



Members of Committee 



Chairman. — Professor W. W. Watts. 

Secretary. — Professor W. G. Fearnsides. 

Professor W. S. Boulton, Mr. E. S. Cob- 
bold, Professor E. J. Garwood, Mr. 
v. C. Tiling, Dr. Lapworth, and Pro- 
fessor J. E. Marr. 



Chairman. — Dr. J. Home. 

Secretary. — Dr. W. Mackie. 

Drs. J. S. Flett, W. T. Gordon, G. Hick- 
ling, K. Kidston, B. N. Peach, and 
D. M. S. Watson. 



Cliairman. — Professor T. W. Edgeworth 
David. 

Secretary. — Professor E. W. Skeats. 

Mr. W. S. Dun, Professor J. W. Gregory, 
Sir T. H. Holland, Messrs. W. Howchin, 
A. E. Kitson, and G. W. Lamplugh, 
Dr. A. W. Rogers, Professor A. C. 
Seward, Mr. D. M. S. Watson, and 
Professor W. G. Woolnough. 



Chairman. — Professor P. F. Kendall. 

Secretary. — 

Professor W. S. Boulton, Professor G. 
Cole, Dr. A. R. Dwerryhouse, Professors 
J. W. Gregory, Sir T. H. Holland, 
and S. H. Reynolds, Dr. Marie 
C. Stopes, Professors J. E. Marr and 
W. W. Watts, Mr. H. Woods, and 
Dr. A. Smith Woodward. 



Cliairman. — Professor E. J. Garwood. 
Secretary. — Professor S. H. Reynolds. 
Mr. G. Bingley, Dr. T. G. Bonney, Messrs. 

C.V. Crook, R. Kidston, and A. S. Reid, 

Sir J. J. H. Teall, Professor W. W. 

Watts, and Messrs. R. Welch and W. 

Whitaker. 



Section D.— ZOOLOGY. 



To nominate competent Naturalists to 
perform definite pieces of work at 
the Marine Laboratory, Plymouth. 



Zoological Bibliography and Publica- 
tion. 



Chairman and Seereta/ry. — Professor A. 

Dendy. 
Sir E. Ray Lankester, Professor J. P. 

Hill, and Mr. E. S. Goodrich. 

Chairman. — Professor B. B. Poulton. 
SecretaTn/. — Dr. F. A. Bather. 
Mr. E. Heron-Allen, Dr. W. E. Hoyle, 
and Dr. P. Chalmers Mitchell. 



XVI 



RESEARCH COMMITTEES. 
2. Not receiving Grants of Money — continued. 



Subject for Investigation, or Purpose 



Members of Committee 



Section F.— ECONOMIC SCIENCE AND STATISTICS. 



Industrial Unrest. 



Chairman. — Professor A. W. Kirkald}'. 

Secretary. — 

Sir H. Bell, Rt. Hon. C. W. Bowerman, 

Professors S. J. Chapman and E. C. K. 

Gonner, Mr. H. Gosling, Mr. G Pickup 

Holden, Dr. G. B. Hunter, Sir C. W. 

Macara, and Professor W. R. Scott. 



Section G.— ENGINEERING. 



To consider and report on the Stan- 
dardisation of Impact Tests. 



Chairman. — Professor W. H. Warren. 

Secretary. — Mr. J. Vicars. 

Professor Payne and Mr. E. H. Sainter. 



Section K.— BOTANY. 



To consider and report upon the neces- 
sity for further provision for the 
Organisation of Research in Plant 
Pathology in the British Empire. 



To consider the possibilities of investi- 
gation of the Ecology of Fungi, and 
assist Mr. J. Rams bottom in his 
initial efforts in this direction. 



The Investigation of the Vegetation of 
Ditcham Park, Hampshire. 



The Structure of Fossil Plants. 



To consider and report upon the neces- 
sity for Further Provision for Train- 
ing and Research in Horticulture. 



Chairman. — Professor M. C. Potter. 

Secretary. — Dr. E. N. Thomas. 

Professors Biflfen and V. H. Blackman, 
Mr. Brierley, Mr. F. T. Brooks, Mr. 
Cotton, Professors Groom and T. John- 
son, Dr F. Keeble, Mr. Pethybridge, 
Mr. J. Ramsbottom, Mr. Robinson, Dr. 
E. J. Russell. Mr. E. S. Salmon, Miss 
Lorrain Smith, Mr. H. W. T. Wager, 
and Miss Wakefield. 

Chairman.— Tir. H. W. T. Wager. 
Secretaries. — Mr. J. Ramsbottom and 

Miss A. Lorrain Smith. 
Mr. W. B. Brierley, Mr. F. T. Brooks, 

Mr. W. N. Cheesman, Professor T. 

Johnson, Dr. C. E. Moss, Professor 

M. C. Potter, Mr. L. Carleton Rea, and 

Mr. E. W. Swanton. 

Chairman.— Mt. A. G. Tansley. 

Secretary. — Mr. R. S. Adamson. 

Dr. C. B. Moss and Professor R. H. Yapp. 

Chairman. — Professor F. W. Oliver. 
Secretary. — Professor F. E Weiss. 
Professor A. C. Seward and Dr. D. H. 
Scott. 



Professor Bateson, Mr. F. T. Brooks, 
Dr. A. B. Rendle, Sir Albert Rollit, 
and Dr. E. N. Thomas. 



RESEARCH COMMITTEES. 

2. Not receiving Grants of Money — contimied. 



xvu 



Subject for Investigation, or Purpose 



Members of Committee 



Section L.— EDUCATIONAL SCIENCE, 



To consider the relations between the 
State and Education, and the means 
of giving effect to proposals for 
Educational Reform. 

The Influence of School Books upon 
Eyesight. 



To consider and report upon the method 
and substance of Science Teaching in 
Secondary Schools, with particular 
reference to its essential place in 
general Education. 



To inquire into the provision of Educa- 
tional Charts and Pictures for display 
in schools. 



Chairman. — Sir Napier Shaw. 
Secretary, — Mr. D. Berridge. 



Chairman. — Dr. G. A. Auden. 
Secretary. — Mr. G. F. Daniell. 
Mr. C. H. Bothamley, Mr. W. D. Kggar, 

Professor R. A. Gregory, Dr. N. Bishop 

Harman, Mr. J. L. Holland, Dr. W. E. 

Sumpner, Mr. A. P. Trotter, and Mr. 

Trevor Walsh, 

Chairman. — Professor R. A, Gregory. 

Secretary Dr. E. H. Tripp. 

Mr. W. Aldridge. Pi-ofessor H. E. Arm- 
strong, Mr. D. Berridge, Mr. C. A. 
Buckmaster, Miss L. J. Clarke, Sir. 
G. F. Daniell, Miss I, M. Drummond. 
Mr. G. D. Dunkerley, Miss A. E. Escott, 
Mr. Gary Gilson, IMiss C. L. Laurie, 
Professor T. P. Nunn , and Mr. A. Vassall. 

Chairman. — Professor H. E. Armstrong. 

Secretary. — Professor R. A. Gregory. 

Mr. D. Berridge, Miss L. J. Clarke, Miss 
Drummond, Mr. O. J. R. Howarth, 
Sir Napier Shaw, and Professor H. H. 
Turner. 



CORRESPONDING SOCIETIES COMMITTEE. 



To take steps to obtain Kent's 
for the Nation. 



Cavern 



Chairman. — Mr. W. Whitaker. 
Secretary. — Mr. W. M. Webb. 
Mr. Mark L. Sykes. 



1018 



Xviii RESEARCH COMMITTEES. 

Eesearch Committees ' in Suspense.' 

The work of the following Committees is in suspense until further 
notice. The personnel of these Committees will be found in the Eeport 
for 1917. 

SECTION B. — CHEMISTRY. 

To report on the Botanical and Chemical Characters of the Eucalypts and their 
Correlation. 

Dynamic Isomerism. 

Chemical Investigation of Natural Plant Products of Victoria. 

SECTION D. — ZOOLOGY. 

An i ivestigation of the Biology of the Abrolhos Islands and the North-west Coast 
of Australia (north of Shark's Bay to Broome), with particular reference to the 
Marine Fauna. 

Nomenclator Animalium Genera et Sub-genera. 

To obtain, as nearly as possible, a Representative Collection of Marsupials for 
work upon {a) the Reproductive Apparatus and Development, (J) the Brain. 

To aid competent Investigators selected by the Committee to carry on definite 
pieces of work at the Zoological Station at Naples. 

To summon meetings in London or elsewhere for the consideration of matters 
affecting the interests of Zoology or Zoologists, and to obtain by correspondence 
the opinion of Zoologists on matters of a similar kind, with power to raise by 
subscription from each Zoologist a sum of money for defraying current expenses of 
the Organisation. 

SECTION E.— GEOGRAPHY. 

To aid in the preparation of a Bathymetrical Chart of the Southern Ocean 
between Australia and Antarctica. 

SECTION G ENGINEERING. 

To report on certain of the more complex Stress Distributions in Engineering 
Materials. 

The Investigation of Gaseous Explosions, with special reference to Temperature. 

SECTION H. — ANTHROPOLOGY. 

To conduct Explorations with the object of ascertaining the Age of Stone Circles. 

To investigate and ascertain the Distribution of Artificial Islands in the Lochs 
of the Highlands of Scotland. 

To investigate the Physical Characters of the Ancient Egyptians. 

To conduct Archseological and Ethnological Researches in Crete. 

The Teaching of Anthropology. 

To prepare and publish Miss Byrne's Gazetteer and Map of the Native Tribes 
of Australia. 

To excavate Early Sites in Macedonia. 

To conduct Anthropometric Investigations in the Island of Cyprus. 

To investigate the Lake Villages in the neighbourhood of Glastonbury in connec- 
tion with a Committee of the Somerset Archaeological and Natural History Society. 

To co-operate with Local Committees in Excavations on Roman Sites in Britain. 

SECTION K. — BOTANY. 

To carry out a Research on the influence of varying percentages of Oxygen and 
of various Atmospheric Pressures upon Geotropic and Heliotropic Ir)itability and 
Curvature. 

The Renting of Cinchona Botanic Station in Jamaica. 

SECTION L. — EDUCATION. 

To inquire into and report upon the Methods and Results of Research into the 
Dental and Physical Factors involved in Education. 

To examine, inquire into, and report on the Character, Work, and Maintenance 
of Museums, with a view to their Organisation and Development as Institutions for 
Education and Research ; and especially to inquire into the Requirements of Schools. 



SYNOPSIS OF GRANTS OF MONEY. XIX 



Syiiopsis of Gh'ants of Money ap^ropiated for Scientific Purposes hy 
the General Committee at the Meeting in London, July 5, 1918. 
The Nam^s of Members entitled to call on the General Treasurer 
for Grants are prefixed to the respective Committees. 

Section A. — Mathematical and Physical Science. 

£ s. d. 

•Turner, Professor H. H. — Seismologicallnvestigations 100 

*Dyson, Sir F. W. — Geophysical Discussions 10 

Section B. — Chemistry. 

•Donnan, Professor F. G. — Colloid Chemistry and its 

Industrial Applications 5 

♦Chattaway, Dr. F. D. — Non-Aromatic Diazonium Salts 7 7 8 

Section D. — Zoology. 
*Bateson, Professor W. — Inheritance in Silkworms 17 

Section F. — Economic Science and Statistics. 

*Scott, Professor W. E.— Women in Industry 10 

♦Scott, Professor W. R.— Effects of the War on Credit, &c.... 10 

Section H. — Anthropology. 

*Marett, Dr. R. R. — Palaeolithic Site in Jersey 5 

♦Myres, Professor J. L. — Archaeological Investigations in 

Malta 10 

*Myres, Professor J. L. — Distribution of Bronze Age Imple- 
ments 10 

* Read, Sir C. H. — Collection and Registration of Photo- 

graphs of Anthropological Interest 10 

* Read, Sir C. H.— Age of Stone Circles 15 

Section I. — Physiology. 
*Schafer, Sir E. S.— The Ductless Glands 9 

Section K. — Botany. 

*Blackman, Dr. F. F.— Physiology of Heredity 15 

*Lang, Professor W.H.— Sections of Australian Fossil Plants 15 
*Lawson, Professor A. A. — Australian Cycadacese 7 17 

Carried forward ^288 4 8 

* Reappointed. 

B 2 



XX CAIRD FUND. 

£ s. d. 
Brought forward 238 4 8 

Section L. — Educational Science. 

*Buckmaster, Mr. C. A.— The ' Free-place ' System 5 

Corresponding Societies Committee. 
* Whitaker, Mr. W. — For Preparation of Report 25 

Total £268 4 8 



Cairo Fund. 

An unconditional gift of lO.OOOZ. was made to the Association at th e 
Dundee Meeting, 1912, by Mr. (afterwards Sir) J. K. Caird, LL.D., of 
Dundee. 

The Council, in its report to the General Committee at the Bir- 
mingham Meeting, made certain recommendations as to the administra- 
tion of this Fund. These recommendations were adopted, with the 
Eeport, by the General Committee at its meeting on September 10, 1913. 

The following allocations have been made from the Fund by the 
Council to September 1918 : — 

Naples Zoological Station Committee (p. xix). — 50Z. (1912-13) ; lOOZ. 
(1913-14) ; lOOZ. annually in future, subject to the adoption of the Com- 
mittee's report. (Reduced to 501. during war.) 

Seismology Committee (p. xii). — 100^. (1913-14) ; 1001. annually in 
future, subject to the adoption of the Committee's report. 

Badiotelegraphic Committee (p. xvi). — 500Z. (1913-14). 

Magnetic Be-survey of the British Isles (in collaboration with th© 
Royal Society).— 250Z. 

Committee on the Determination of Gravity at Sea (p. xvi). — 1001. 
(1914-15). 

Mr. F. Sargent, Bristol University, in connection tvith his Astro- 
nomical Work. — 101. (1914). 

Organising Committee of Section F {Economics), towards expenses of 
an Inquiry into Outlets for Labour after the War. — lOOZ. (1915). 

Bev. T. E. B. Phillips, for aid in transplanting his private observa- 
tory.— 201. (1915). 

Oceanographical Laboratory, Edinburgh. — lOOZ. (1916-17). 

Committee on Fuel Economy. — 25Z. (1915-16). 

To arrange Meetings and Discussions on Geophysical Subjects. — 61 . 
(1917-18). 

Sir J. K. Caird, on September 10, 1913, made a further gift of l.OOOL 
to the Association, to be devoted to the study of Radio-activity. 

* Eeappointed. 



REPOETS 



ON THE 



STATE OF SCIENCE, ETC. 



REPORTS ON THE STATE OF SCIENCE, Em 



Seismological Investigations. — Twenty -third Report of the Com- 
mittee, consisting of Professor H. H. Turner (Chairman), 
Mr. J, J. Shaw (Secretary), Mr, C. Vernon Boys, I)r. J. E. 
Crombie, Mr. Horace Darwin, Dr. C. Davison, Sir F. W. 
Dyson, Sir R. T. Glazebrook, Professors C. G. Knott and 
H. Lamb, Sir J. Larmor, Professors A. E. H. Love, H. M. 
Macdonald, J. Perry, and H. C. Plummer, Mr. W. E, 
Plummer, Professors R. A. Sampson and A. Schuster, Sir 
Napier Shaw, Dr. G. T. Walker, and Dr. G. W. Walker. 

General. 

Owing to the cancelling of the Cardiff meeting proposed for 1918 and 
to other reasons connected with the war, the present Report is made brief. 
It has been drawn up by the Chairman. 

The Committee asks to be reappointed with a grant of lOOl. (including 
printing), in addition to 100^. from the Caird Fund already voted. The 
grant was formerly 60i., with 701. for printing ; 130?. in all ; but during 
the war it has been reduced to lOOl., partly to meet the need for economy, 
partly because the printing has necessarily been less. The Government 
Grant Fund administered by the Royal Society has voted a subsid)^ of 
200^ for 1918 as in recent years. With the above modification the budget 
remains practically the same as given in the Twentieth Report. 

Owing to business reasons connected with the war, Mr. J. H. Burgess 
found it necessary to leave the Isle of Wight at the end of March, 1918. 
For half a dozen years he had devoted a considerable portion of his time 
(nominally one-half, but this was often exceeded in his enthusiasm for 
seismology) to the work at Shide. The Committee is greatly indebted 
to him for his prompt and valuable help when the sudden death of John 
Milne in 1913 left them in face of a threatened break in the work. Thanks 
to the special knowledge IVIr. Burgess had acquired in working with Pro- 
fessor Milne, discontinuity was avoided, and whatever changes are found 
necessary in the future can be made with full consideration. 

Mr. S. W. Pring remains at Shide for the piesent, though it is impossible 
to predict the length of his stay under present war conditions, which 
have already somewhat reduced the time he is able to devote (chiefly in 
the evenings) to seismology. His knowledge of Russian, which originally 
brought him into contact with Professor Milne, has been an important 
asset throughout, and has recently proved specially valuable in supplying 
translations of papers otherwise inaccessible. 

The routine work generally is now in the hands of Miss Caws, who 
had been trained in it by Mr. Burgess. As a safeguard against her illness, 
and to enable her to take an occasional Jioliday, Miss E. F. Bellamy, of 



4: REPORTS ON THE STATE OF SCIENCE. — 1918, 

the Oxford University Observatory, has been instructed by Miss Caws 
in the work, and undertook the routine observations during the absence 
of Miss Caws from the middle of July to the middle of August. It is 
proposed to set up at least one Milne-Shaw seismograph at Oxford under 
Miss Bellamy's care. Mr. James Walker has kindly placed at the disposal 
of the Committee the basement of the Clarendon Laboratory iri which 
Mr. C. v. Boys made his gravity determination. The suitability of 
Oxford as an observing site can thus be tested under good conditions, 
and the results of the tests in a basement of that character may have 
an even wider application when plans for the future come to be discussed. 

Finally, since the departm-e of Mr. Burgess naturally reduces the 
Working power of the staff, Miss Bellamy has been definitely transferred 
to the seismological service for the present. This transference was approved 
by the Board of Visitors of the Oxford University Observatory ' as a 
provisional and possibly temporary arrangement ' which ' is not to pre- 
,]udice the resumption of her position as Assistant [in the University 
Observatory] at the conclusion of the experiment, should that be her 
wish.' The nature of the experiment here mentioned has perhaps been 
sufficiently indicated, but a few words of explanation may be added for 
the sake of clearness. 

It was mentioned in last year's Keport that the question of the future 
of seismology had attracted the attention of more than one body. Besides 
our own Committee, the Geodetic Committee of Section A of our Associa- 
tion, in discussing plans for a Geodetic Institute, were led to consider 
the possible association, in such an institute, of other branches of Geo- 
physics with Geodesy. It was further mentioned that the Geodetic 
Committee had thereupon been suitably enlarged for the purposes of 
this discussion ; and it should perhaps have been added that they had 
been invited by the Conjoint Board of Scientific Societies to act as their 
Committee also, and to report to them as well as to the British Associa- 
tion — and had, with the approval of the Council of the British Association, 
accepted that invitation. 

Their report was in favour of the association of the three branches 
Geodesy, Seismology, and Tides in one Geophysical Institute. It was 
generally approved by the Conjoint Board, who appointed a small Execu- 
tive Committee to formulate definite plans. 

The transference of some of the Shide work to Oxford during the next 
year or two is definitely not intended to prejudice, or to embarrass in 
any way, the discussion of these plans. But since we are in several 
respects somewhat in the dark (e.g., as to the precise value of a basement 
as a site for instruments, of a University as a centre of organisation, &c.), 
the transference will provide experience which may possibly be of some 
assistance to the discussion. Meanwhile, it is also the simplest solution 
of the question of ways and means at the present rather difficult time. 

Instrwnental. 

The wireless time-signals have been received at Shide regularly, with 
some interruptions owing to derangement of the apparatus. The transit 
lent by the Royal Astronomical Society has been in reserve, but not much 
used during the year. 

Towards the end of 1917 the temporary use of a ' dug-out,' constructed 



ON SEISMOLOGICAL INVESTIGATIONS. 5 

for military purposes, was offered to Mr. Burgess, and the opportunity 
was taken to make some experiments. With Mr. Shaw's help the Milne- 
Bmgess machine was dismounted from its pier at Shide, and remounted 
in the dug-out some few miles away. At some considerable personal 
trouble and inconvenience Mr. Burgess kept the machine running for a 
few weeks. [It was necessary to keep a pump going to avoid having 
the dug-out flooded.] No very satisfactory results were obtained, the 
wandering of the trace being just as serious as at Shide, and the experi- 
ments came to a natural end when the dug-out was reclaimed for militarj' 
pm'poses. The main conclusion which emerged from the experiments 
was that rain had more to do with the wandering of the trace than had 
temperature. After rain the lines became much congested : when the 
rain ceased they were unusually expanded, returning to the normal separa- 
tion when the weather had been fine for a few days. The inference 
seems to be that the wetting and drying of the ground caused slow move- 
ments in opposite directions — a conclusion in accord with previous ex- 
perience at Shide. The dug-out was in a clay soil, which doubtless 
emphasised the effects. 

Milne-Shaw Seismographs. 

Several of these machines are nearing completion ; that intended 
for Oxford is finished, and will be erected as soon as possible. 

Suggested Corrections to Adopted Tables. 

The work of disentangling the corrections to the adopted tables from 
other errors is attended with considerable difficulties, but nothing is more 
important, if the phases are to be rightly identified ; and although pro- 
gress is slow, the ground is being steadily cleared. One set of difficulties 
arises from ignorance of the clock errors, which may be expected especially 
at outlying stations. Recent experience aroused the suspicion that 
these are often considerable, so that accurate intervals S — P are attended 
by unexpectedly large errors in S and P separately. The experience 
here referred to is derived from the re-reduction of a number of the best 
observed earthquakes after applying the corrections to tables deduced in 
the last report, and carefully correcting the position of epicentre. 

Hence attention was recalled specially to the investigation in the 
Introduction to ' The Large Earthquakes of 1913,' p. iii, which was con- 
fined to the use of intervals S — P, free from clock errors. This investigation 
gives no information about S and P separately which will enable us to 
correct the tables, and was naturally followed by a more comprehensive 
analysis where S and P were kept separate, the results of which were 
given in the Twenty-second Report, Table II. We may denote these two 
investigations by the symbols (1913) and (22) respectively. 

Now for the smaller values of A (1913) differs essentially from (22), 
as is seen from Table I. below, and we must determine which is nearer 
the truth. For this the following method suggested itself. 

Pairs of Stations on Opposite sides of tJte Epicentre. 

Any pair of observing stations on directly opposite sides of the epi- 
centre give a check on the values of S — P. Suppose for simplicity we 



REPORTS ON THE STATE OP SCIENCE. — 1918. 



had two stations, A and Z, at ends of a diameter of the earth, jand the epi- 
centre E lay midway between them, so that EA=EZ=90°, for which 
the tables give S-P=658 seconds. We are suggesting that this ought 
to be 658s.— 17s.=641 seconds. If we are right, then 641 seconds will 
be observed at both A and Z. In proceeding to determine the epicentre 
we may use A alone (for in practice A may not be a single station but the 
whole body of European stations), and using our erroneous tables we 
should put the epicentre only 86°-8 from A, and therefore 93°-2 from_ Z ; 
so that the observed 641 seconds at Z would be doubly in defect, since 
for 93°-2 the tables give 674 seconds. However we _ determine the 
epicentre (provided A i and A 2 are not too imequal), this double defect 
of 33s. or 34s. will be shared between A and Z. Two such antipodal 
stations are specially valuable because we cannot alter the sum of the 
two distances ( Ai+ Az) by changing the azimuth of the epicentre ; and 
even when the antipodal condition is not quite fulfilled (as, say, for Pulkovo 
and Riverview, which are about 140° apart) a change of azimuth makes 
very little change in A^+Az- For pairs of stations closer to the 
epicentre, the azimuth is often well determined by other stations ; and 
unless they are very close to the epicentre the azimuth error only affects 
( A 1+ A 2) to the second order. Hence we have a good check on the 
values of S— P. The following satisfactory instances were collected from 
the published results of 1913, 1914, 1915. They are worth giving in 
detail to show the good accordance. 

Table I. 
Pairs of Stations on opposite sides of the Epicentre. 



Al 


A2 


Mean 

c 


(S-P)i 


(S-Pk 

s. 


Mean 








6. 


s. 


6-0 


6-9 


6-4 


+39 


-10 


+14 ; 


7-0 


18-7 


12-8 





^- 7 


+ 4 


6-9 


19-9 


12-9 


+22 


+ 6 


+ 14 


5-9 


20-4 


13-2 


+ 7 





+ 4 


7-8 


20 


13-9 


+ 12 


+26 


+ 19 


9-9 


19-4 


14-6 


+ 30 


- 2 


+ 14 


9-9 


223 


161 


+ 4 


+ 8 


+ 6 


18-6 


231 


20-8 


+ 1 


-21 


-10 


14-8 


300 


22-4 


+ 14 


-10 


+ 2 


22-8 


362 


29-5 


- 3 


- 5 


- 4 


26-3 


36-8 


316 


- 1 


- 4 


- 2 


20-8 


53.1 


37 


+ 8 


-21 


- 6 


25-9 


49 


37-4 


— 7 


+ 4 


- 2 


26-2 


78-4 


62-3 


+ 2 


- 9 


- 4 


40-2 


69-5 


64-8 


-32 


-i-15 


- 8 


47-8 


86-3 


67 


- 9 


-21 


-16 


47-2 


87 


67 1 


-20 


-10 


-15 ; 


460 


88-2 


67 1 


-20 


-24 


-22 i 


58-6 


791 


68-8 


-27 


-10 


- 18 1 


60-3 


88-5 


69-4 


- 8 


-12 


-10 


48-9 


90-6 


69-8 


-13 


- 3 


- 8 


65-6 


751 


70-3 


-12 


-15 


-14 


68-5 


73-5 


710 


-12 


-10 


-11 


43-6 


90-9 


72-6 


- 8 


-11 


-10 


63-9 


81-4 


72-6 


- 1 


-18 


- 9 


661 


81-6 


73-8 


+ 3 


-14 


- 6 



ON SEISMOLOGICAL INVESTIGATIONS. 



Forming groups of tlicse wo obtain the mean values of Table II. 

Table II. 
Suggested Corrections to Tabular S — P. 



No. in Group [ 


Mean A 


'Mean Correction 


(1918) 


(22) 


1 


o 


s. 


B. 


s. 


1 


6-4 


+ 14 


+ 4 


- 4 


4 


13-2 


+ 10 


+ 8 


- 8 


4 


18-5 


+ 3 


+ 3 


- 8 


4 


330 


- 4 


-10 


-13 


2 


53-6 


- 6 


- 7 


- 6 


6 


68-2 


-15 


- 4 


- 6 


5 


72 1 


-10 


+ 1 


- 8 



We infer that for the smaller values of A at any rate the investiga- 
tion (1913), in which only S— P was used, is to be preferred to (22), in 
which S and P were treated separately. 

Observations o/ PRv and SRi. 

But a knowledge of S— P will not suffice to coirect the separate 
tables. We must find some other way of doing this, and recourse was 
had to the observations of PR] and SRi. 

We shall first assume that these represent reflections at the mid-point 
without loss of time. Thus PR] is a P wave reflected at the mid- point 
(M) between the epicentre (E) and the observing station (0) so that 

E0=2EM=A, 

and the time for PRi is twice that for EM or A /2. 

In Table III. the first column gives A and the second gives the observed 
value of i(S4-P)-PRi,or as we may write it |(S-P)+P-PRi, which 
is nearly constant. The observations were collected from the records 

Table III. 



1 A 


Obsd. 

s. 


Tables 

s. 


0-C, 


O-C2 




s. 


s. 


! 23 


77 


98 


-21 


-15 


28 


75 


102 


-27 


-14 


33 


80 


103 


-23 


- 9 


38 


83 


100 


-17 


- 2 


43 


88 


95 


- 7 


T 5 


48 


91 


88 


+ 3 


+ 10 


53 


95 


85 


+ 10 


+ 10 


68 


98 


83 


+ 15 


+ 10 


63 


102 


82 


+20 


+ 8 


68 


106 


83 


+23 


+ 11 


7a 


109 


87 


+22 


+ 11 


78 


109 


92 


+ 17 


^ 9 


83 


106 


92 


+ 14 


+ 9 


88 


105 


96 


+ 9 


+ 7 


93 


102 


101 


+ 1 


+ 4 



of several observations, especially Pulkovo, in the years 1914 and 1915, 
and are fairly numerous for all but the small values of A. The actual 



8 



KEPORTS ON THE STATE OF SCIENCE. — .1918. 



figures given in the table were read from a smoothed curve. In the third 
column is given the corresponding quantity calculated from the adopted 
tables in use, followed in the fourth column by the differences 0— Cj. 
In the next column 0— C2 is shown the effect of correcting these tables 
as in Table II. of the 22nd Report. It is seen at a glance that the tables 
are considerably in error, and that the suggested corrections reduce the 
errors. But before deciding to attempt any further reduction let us 
turn to the observations of SRi, of which the following were collected : — 

Table IV. 
Observed Values o/SRi. 



S-P 


SRi-S 


Diff. 


S- 


s. 


s. 


363 


149 


214 


366 


146 


220 


372 


162 


210 


397 


195 


202 


(374) 


(163) 


(211) 


525 


234 


291 


630 


249 


281 


541 


266 


275 


542 


263 


279 


560 


257 


293 



(538) (254) (284) 



S-P 


SEi-S 


Diff. 


s. 


s. 


s. 


574 


282 


292 


578 


291 


287 


583 


297 


286 


(578) 


(290) 


(288) 


606 


332 


274 


634 


341 


293 


647 


382 


265 


673 


3.57 


316 



(640) (353) (287) 



The records of SRj are often given to tenths of a minute only, 
suggesting some uncertainty ; more observations are desirable, but 
those above quoted are consistent in showing that the difference (S — P) 
— (SRi— S) or 2S— P-SRi is sensibly constant from (say) S— P 
=520 seconds to 680 seconds, which may serve as a useful check. 

Comparing the means (in brackets) with the adopted tables, we get 
the differences — C, while the corrections of the 22nd Report give 
the column — C2. 

Table V. 
2S-P-SR,. 



S-P 


A 


Calc. 


Obs. 


0-Ci 


0-C.j 


s. 


0. 


s. 


s. 


s. 


s. 


374 


40-3 


212 


211 


- 1 


+ 6 


538 


680 


220 


284 


+64 


+33 


578 


75-2 


241 


288 


+47 


+21 


640 


86-5 


272 


287 


+ 15 


+ 9 



We again see at a glance that the adopted tables are sensibly in error, 
and that the corrections found in the 22nd Report, while they reduce 
these errors, do not annihilate them. We must proceed further in the 
s.nme direction. 

It is easily seen that the further alterations mu&t be chiefly in SRj, 
and not in S (or P). Thus let us fix attention on the worst case, where 
S— P=538s. For this value of S— P the adopted tables give A=68°-0 ; 
but when we correct the tables we get :i=69°-2. Note that S— P is 



ON SEISMOLOGICAL INVESTIGATIONS. 



the observed quantity, and A is only inferred. But the consequent 
change in (S— P)+(S — SR) is small and in the wrong direction ; for though 
S is increased by U seconds, SR, is increased by 18 seconds. After 
altering A we have, however, still to apply the errors of S and of SR, . 
The complete process may be represented thus, when the corrections 
used are those of tlie 22nd Report : — 





S-P 


A 


^A 


+ s 


-SB, 


(S-P) + (S-SRi) 


Tables 

A 
Errors 


. 538 


680 
+ 1-2 


sl-o 

+0-6 


+ 1202 

+ 14 
- 3 


-1520 
- 18 
+ 38 


+220 
- 4 
+ 35 



We see at a glance that the efficient corrective is the error in SR, which 
is taken to be twice that of S at A/2. The error of S at 34°-6 is found 
in the 22nd Report to be —19 seconds ; if this were only larger numeric- 
ally, say —34 seconds, we could completely destroy the + 64s. of Table 
v., column 0— C,. 

The observations of SR, are not, however, so numerous as those of 
PR, to which we now return. Let us neglect the small change in A. 
Beginning at the bottom of the table, let us assume that we know that 
the error at A=93° is —7 seconds, from the 22nd Report. Then, since 

P-PR, = +ls. 

PR, = P-ls.= -7s.-ls.= —88, 

i.e. the error at A = 46°-5 = — 4s., which so far accords quite well with 
that deduced independently in the same Table II. of the 22nd Report. 
But as we proceed upwards we shall not find the same good accordance. 
The errors for the smaller values of A deduced in this way from PR, 
are as in Table VI. : — 

Table VI. 

Errors of P deduced from PR,. 



A 


From PR, 


From (22) Old Tables 5P, 


New 


Possible 8P3 
s. 


Corrn, 







s. 


s. 


.". 8. 


11-5 


+ 10 


+ 1 


172 
34 


182 
35 


184 
36 


+ 12 


14-0 


+ 11 


+ 1 


206 
33 


217 

29 


220 
31 


+ 14 


16-5 


+ 7 


+2 


239 
30 


246 

27 


251 
25 


+ 12 


19-0 


+ 4 


+2 


269 
30 


273 

26 


276 
18 


+ 7 


21-5 





+ 1 


299 
29 


299 
26 


294 
21 


- 5 


24-0 


- 3 





328 

25 


325 

24 


315 
25 


-13 


26-5 


- 4 


-1 


353 
25 


349 
23 


340 

26 


-13 


29-0 


- 6 


-3 


378 
24 


372 

22 


366 
25 


-12 


315 


- 8 


-4 


402 
23 


394 
21 


391 
24 


-11 


34 


-10 


-6 


425 
21 


415 
21 


415 

22 


-10 



10 



REPORTS ON THE STATE OF SCIENCE. — 1918. 



Table VI. — continued. 
Errors ofP deduced from PRi. 



A 


From PRi 
-10 


From (22J Old Tables SP 


New 


Possible 8P3 


Corm. 


36-5 


-6 


446 


436 


437 


- 9 








20 


21 


21 




390 


- 9 


-7 


466 
21 


457 
22 


458 
21 


- 8 


41-5 


- 8 


-7 


487 
19 


479 
20 


479 
20 


- 8 


44-0 


- 7 


-6 


506 
18 


499 
21 


499 
20 


- 7 


46-5 


- 4 


-4 


524 


520 


519 


- 6 



We see that the investigation of the 22ncl Report (shown in the third 
column of Table VI.) fails for the smaller values of A in much the same 
way as is manifested in Table II. above ; viz. from A = 10° to A = 20° 
the errors are not sufficiently positive if we may accept the indications 
of PRi, while near A = 35° they are not sufficiently negative. The 
column deduced from PRj starts with a hill and falls into a valley ; in 
the investigation (22) the hill is cut down and the valley filled up ; and 
it is reasonable to attribute these modifications to the effects of compro- 
mise due to the determination of the epicentre with the faulty tables. 

In the fourth and succeeding columns of Table VI. the effects of 
applying the newly-suggested corrections are shown. First, imder the 
heading ' Old Tables ' are given the tabular values for P, followed by the 
differences 8P]. Under the heading 'New' are given the tables with 
corrections as from PR, and the differences 8P2. Now it is seen that 
these differences ^P2 are approximately constant from A=29°-0 to 
A = 46°-5, whereas SP, drops steadily. We are reminded of the phe- 
nomenon shown by the Pidkovo angles of emergence. (See p. 54 of 
Dr. G. W. Walker's ' Modern Seismology '). In the last report Dr. Walker 
recalled attention to these observations, emphasising G-alitzin's belief 
in them, and suggesting in explanation a focal depth of the order of 1,300 
km. _ No support for this hypothesis has been otherwise forthcoming, 
and it seems possible that a simpler explanation may be found in errors 
of the tables ; for a comparatively slight further modification would 
give angles of emergence in fair accord with the Pulkovo observations. 
Such a modification is shown in the column of Table VI. headed ' possible.' 
Its differences 8P3 show a fall to A = 20°, then a rise to about A = 28°, 
and then a fall again, which is all that is required. We proceed to show 
that this possibility is independently suggested by a study of the Y 
phenomenon or polychord. 

The Polychord or Y Phenomenon. 

Is it simply PR 5 ? 

In the 21st Report the following approximate times were deduced 
from the earthquake of 1913, March 14, for the Y phenomenon :— 



Time for Y = 
Average vel. 



95° 
1420s. 
14-9S. 



100° 
1470s. 
14-7s. 



105° 

1490s. 

14-2S. 



110° 
1520s. 
13-8S, 



ON SEISMOLOGICAL INVESTIGATIONS. 



11 



The average velocity, added in the last line, falls off very definitely, 
and the hypothesis of a ' polychordal ' P wave transmitted by numerous 
reflections with approximately uniform arcual velocity was therefore 
withdrawn. But in the course of the examination of Dr. G. W. Walker's 
hypothesis of deep-seated focus a modification of the hypothesis suggested 
itself which seems worth attention. Repeating the suDJoined figure from 
the 20th Report, 




B 



we shall assume that cC is an arc of 17°-1 so that a P wave starting from 
a deep-seated focus E along EC will be reflected at C so as to strike the 
surface again at Ci C2 C3 . . . where CC, = C1C2 = C2C3 . . . = 17°-1 ; 
and after five such reflections will reach a distance A from K Cthe epicentre) 
equal to 5-5 X l'i°-l = 94°. The whole time required would be, with 
adopted tables, 

5-5 X 246s. = 1353s., 

but if we adopt the corrections of Table VI. as in the column ' New * 
we should get 

5-5 X 253s. = 1391s. 

The value extrapolated from the above-quoted values for Y would 
be still greater, viz. 1410s., but we see at once that a comparatively 
slight increase to the tables would give this exact value : viz. the time 
for an arc of 17°-1 must be 256s., indicating a correction to tables of -f- 10s. 
near A = 17° instead of + 7s. 

For paths slightly differing from EC, such as Ea or EB, the chords 
are greater, and five reflections will bring us beyond 94" in either case ; in 



12 REPORTS ON THE STATE OF SCIENCE. — 1918. 

fact, there can be no PR5 when A is much less than 94° (for the actual 
limit see below), which accords with the facts of the quake of 1913, 
March 14, from which the above figures were deduced in the 21st Report, 
if we exclude a doubtful Pulkovo observation. This limiting value for 
A gives us in fact the arc 17°'l, and consequently the depth of focus. 
If EC be a straight line we find EK = 0-011 of the radius ; say 44 miles 
or 70 km. These figures apply only to this particular earthquake, and 
will also require modification if the path cC is curved ; but they give 
the order of quantity suggested. 

As we pass to greater values of A the wave must start along Ea or EB. 
If it starts along Ea, the total length of path will be less than 5 ' 5a A, and 
cannot be so small as 5'0 aA. If it starts along EB the length will exceed 
5.5bB or 5"5aA. 

Thus A=110° may be reached in two ways : either by (let us say for 
illustration) 5 reflections or 6. The times of transmission would be (using 
column ' New ' of Table VI.) :— 

5 X time for 22° = 6 x 304s. = 1520 seconds, 

6 X time for 18-3° = 6 x 266 = 1696 seconds, 

and since we observe the earliest disturbance we fix attention on Ea and 
neglect EB. 

Assuming the paths of the waves to be straight lines as in the figure, 
let cC subtend an angle 20 at the centre ; and let aA, inclined to cC at 
an angle ff>, subtend an angle 2A at the centre. Then 

cos A=cos C cos (f>=cos, 8°*55 cos <ji 
arc Ka=A — ^. 

In Table VII. are given, for various values of (f>, first the arcs 2A 
and A — <^, then the whole arcs 10A+(A— <^) ; then the estimated 
times for Y from the figures quoted above from the 21st Report. From 
these we subtract the time for the arc A— ^, which we can estimate only 
approximately by taking it as 

arc in degrees x 14-9s. 

The remainder, divided by 5, gives the time for the arc 2A, below 
which is subjoined the present tabular value and the necessary correction, 
followed by the correction deduced from PRi in Table VI. 



2A . 

A—<t> 
Whole arc 



Whole time 

Time of (A-<^^ 
Time of 2A 
Tables 
Correction 
Table VI. 

The last two lines are not very different, and we notice that the cor- 
rections now suggested are generally similar in form to those formerly 





Table VII. 























00 


30 


50 


60 


7 


171 


180 


19-8 


20-8 


22-0 


8-6 


60 


4-9 


4.4 


40 


940 


960 


103-9 


108-4 


114-0 


s. 


s. 


9. 


8. 


8. 


1410 


1430 


1485 


1512 


1548 


128 


89 


73 


66 


60 


256 


268 


282 


289 


298 


246 


257 


279 


291 


305 


+ 10 


+ 11 


+ 3 


- 2 


- 7 


+ 6 


+ 5 


+ 3 


+ 1 


- 1 



ON SEISMOLOGICAL INVESTIGATIONS. 13 

found, but greater in amount. As has been remarked above, the existence 
of a hill and valley in the curve, which compromise has obliterated, is 
quite a fair possibility. 

The question, however, whether the observations can be fitted to so 
considerable a hill and valley can only be answered after laborious 
re-reduction ; such examination as has been made is not impromising. 
but is embarrassed by the imcertainties of clock error already referred 
to. A glance at the records, for instance, of 1913, January 27, will show 
the doubtful nature of the records near the epicentre. 

The explanation above suggested brings with it a number of questions. 
Firstly, why should PRs be specially prominent, compared, say, with 
PR4 or PRe ? The answer is that PRg happens to fall in a place where 
it can be mistaken for S, while the others do not. But the suggestion 
of a sensible focal depth necessitates the re-investigation of other 
reflected waves, especially of PR^. We notice two important points. 

Firstly, the wave which starts along EC reaches the surface as PRj 
at A=8°-6-|-17°-l=25°-7 ; and it might at first sight appear that 
we cannot have any PRj for a value of A less than this, for the arcs 
2A and 2B are both greater than 2C, as already remarked. But a wave 
starting along Ea reaches the surface after one reflection at 

A = 2A + A — <^, 

and from Table VII. we see that the sum of these quantities diminishes 
at first, though it ultimately increases. The minimum value is given 
by the condition 

d<^=3dA, 

which leads to 

(32-l)sin V^tan^C 
whence ^=3°, A =24°. 

Within A = 24", then, no PRj can be received. 

Now, the evidence is distinctly in favour of the existence of some 
inferior limit for A of this kind. Within A = 24° the records are few 
and discordant, and the lowest value of S — P, hitherto found for 
which PR, has been recorded is 204 seconds, corresponding to A = 18°, 
or a focal depth of, say, 25 miles. A more extended investigation of 
this point must, however, be deferred. 

The second point is that at the point C (where A=25°-7) PR, arrives 
not by means of two equal arcs of 13°, but by unequal arcs of 8°-6 and 
17°-1. Hence the tabular computation of Table VI. becomes misuitable. 
Using the adopted tables we should get for A =26° by equal arcs of 
13°, -1- (S+P)-PRi=99 seconds, by arcs of 8°-7 and i7°-3 i (S-j-P,) 
=105 seconds. Hence the large negative values of 0— C, at the head 
of Table III., should be still further increased ; and, moreover, when we 
deduce from them corrections to P the dividing factor is 1-5 instead of 
2-0, and the corrections apply to larger values of A, all of which changes 
emphasise the positive corrections to P for small values of A. As above 
remarked, however, EC does not give the minimum PRi, which is for 
A =24°, by arcs of 6° and of 18°, 1 (S+P)-PRi=107 seconds, the 
computation by equal arcs giving 98 seconds. 

1918. o 



14 REPORTS ON THE STATE OP SCIENCE.— 1918. 

For greater values of A PR, may come by either of two paths. It 
is easy to take from a diagram the alternatives as follows ;- 



A. 

Arc (A-<^) . 
Ix)ng arc 


= 24 

60 

. 18-0 


25 

4-5 

20.5 


26 

4 

220 


27 

.S-6 

234 


28 
3 3 

24-7 


29 

30 

260 


30 

2-7 
27-3 


1 (S+P)-PR, 


s. 
107 


8. 

113 


s. 
118 


122 


R. 

127 


a, 
133 


s. 
138 




o 


O 


o 


O 


O 


o 


c 


Arc {A + <t>) . 
Long arc 


. 60 
. 180 


8-0 
17 


8-9 
17-1 


9-7 
17-3 


10-6 
17-5 


113 
17-7 


12-0 
18 


i (S+P)-PRx 


s. 
, 107 


s. 
104 


s. 
104 


s. 
105 


s. 
106 


s. 
107 


s. 
150 



Here it certainly looks as though the observed PR, starts with the 
longer arc A-\-<f> instead of the short arc A — <f> as we have assumed 
for PRs ; for only by this supposition can we obtain approximate con- 
stancy for the quantity -|- (S+P)— PR,. There is nothing unreasonable 
in this difference between the two cases : for PRg, if we are right in 
identifying it with Y, is usually read for S ; we read the first big move- 
ment, and, as already remarked, the PR5 by A-|-^ follows that by 
A — <f>. Hence the former is read. But in looking for PR, we should 
naturally take a movement which is not too near P. The PR, which 
starts with A — <f> runs up closer and closer to P as <^ increases. 

We have, however, stiU to explain why (S-t-P)/2— PR, should be 
about 105s. instead of about 80s., as at the head of the ' observed ' column 
in Table III. On the present hypothesis the tables are wrong to this 
extent. When A =28°, for instance, if we take the last column of Table 
VI. the error of P is — 12e. and that of S shoidd be nearly double, say —20s., 
which gives for (S-t-P)/2 an error of — 16s. : and PR, is in error by 2 x 14 
=28s. ; making altogether 44s., which reduces the 106s. of the tables 
to 62s., as compared with 75s. observed. These corrections are apparently 
too large, and it may be readily admitted that the last column of Table 
VI. probably goes too far. ' If w^e use the first column we get, say, —8s. 
for (S-f P)/2, and —22s. for PR,, wliich is just the quantity required. 

Somewhat similar considerations apply to PR2- The whole arc is 
now 

A-<t>+iA, 

and becomes a minimum when 

d<^=5dA, 
which leads to 

(52-I) sin2 <^=tan2 C. 

so that <f>=l°-7, A=8°-75 : minimum A =42°. 

Generally, for PRn, the corresponding equation is 

{(2nfl)2-l}sin2<^=tan2C, 

or (2n-|-l)</)=C approximately; so that when n=5, «^=0°-77, A=8'' 58 ; 
minimum arc being 93°-6, close to the value obtained by starting along EC. 



ON SEISMOLOGICAL INVESTIGATIONS. 15 

Observations of PR2 are fairly numerous beyond S— P=542 seconds 
(say A=69°), but only three have been found for smaller values, viz. : 

S - P = 487s., 3638., 360s. 
Say A = 59°, 38°.5, SS^.O, 

according to adopted tables. Further scrutiny is of course desirable 
but the evidence is so far satisfactory. 

Of PR3 and PR4 little more need be said at present than that they 
do not fall near enough to S to be confused with it, while PR^ probably 
lies beyond S. The rough minima in A for their appearance are : 





PR3 


PR, 


PR, 


PR, 


A = 


60° 


77° 


94° 


111° 




s. 


s. 


s. 


s. 


Time = 


896 


1152 


1408 


1664 


S (Tables) = 


1103 


1309 


1496 


1657 


S (corrected) = 


1102 


1300 


1474? 


1637 ? 



The above notes are obxaously tentative and incomplete, but they 
represent the result of a good deal of work by the method of trial and 
error, and may serve to show possibilities. Especially is it hoped that 
they may show the importance of an identification of the phenomena 
through more accurate tables of P and S, on which the main computing 
strength of the Shide organisation is being concentrated for the present. 
It may be that there are too many variable elements to make great 
accuracy possible, but experience of working with the residuals suggests 
the contrary view, which is at any rate worth thorough testing, even 
if the ultimate result be disappointing. 



Preliminary Report on Tides and Tidal Currents. 
By H. Lamb and J. Proudman. 

It seemed most important in the first place to obtain a sort of con- 
spectus of what has been done and what is in progress, in the way 
of observation and reduction, in various parts of the world. Owing 
to the circumstances of the time our attention has been mainly confined, 
so far, to work done in the British Empire and in the United States 
of America. As regards Great Britain, the more accessible literature 
has been consulted, whilst for India, Canada, Australia, New Zealand, 
and the United States valuable information has been furnished by 
various authorities, to whom special acknowledgment will, it is intended, 
be made in a more complete Eeport. 

It is proposed in the future Eeport, or Reports, to give an account 
of the work done in the countries named, together with a critical 
examination of such points as appear to call for it. 

In the course of the survey so far made, various suggestions have 
naturally presented themselves, some of which may indicate lines of 
research. The following may be mentioned: — 

1. While the tide-tables as at present produced appear to be adequate 
for practical needs, the possibility of improvement should not be left out 

c2 



16 KEPORTS ON THE STATE OF SCIENCE. — 1918. 

of sight. There are many oases where the harmonic constants have 
not been determined with all the accuracy obtainable. 

2. Harmonic analyses, and possibly more extended observations, 
relating to oceanic island stations appear to be wanting. These would 
probably give results of great theoretical value. 

3. Continuous observations of tidal heights at off-shore stations are 
especially desirable, both as a test of hypotheses relating to the main 
tidal movements and as a foundation for more complete syntheses of 
tidal facts. 

4. Further continuous observations of currents are also desirable. 
The only British observations of this kind which have been analysed 
appear to be those taken in and near the North Sea in connection with 
the " Conseil permanent international pour 1 'exploration de la mer. " 

5. Greater accuracy seems attainable in the harmonic analysis, 
more particularly, of the smaller semidiurnal and diurnal tides. "When 
a year's record is treated by the methods in common use, only the 
numbers obtained for the larger tides can be assumed to be reasonably 
correct. Improvement may be sought by allowing for imperfect isola- 
tion of the different series. This is done by the U.S. Survey, but 
revised methods appear necessary except for the principal solar series. 

6. Accurate determinations of the constants for the long-period tides 
of astronomical origin are much wanted, on account of the part which 
these tides play in various speculations. The numbers obtained by 
analysis of a single year's record are very uncertain, not through 
defect in the method of reduction, but in consequence of meteorological 
disturbances in the record itself. The analysis of observations extend- 
ing over a long series of years might be expected to give more trust- 
worthy results. 

7. A comparative study should be instituted of the geographical 
distribution of well-attested harmonic constants for tides of different 
periods. This might lead to an improved dynamical conception of 
the great tidal movements. 

8. A knowledge of the free periods of oscillation of the ocean, 
or of special regions of it, would be of the greatest interest, not 
only for its own sake, but as a basis for dynamical reasoning on 
the actual forced tides. It is not known whether any attempt has 
been made in this direction by an examination of the results obtained 
for different ports whose harmonic constants have been accurately 
determined when the predicted tide is subtracted from the observed. 
The residue might conceivably yield some indications as to the longer 
free periods. A further examination of the records attending such a 
disturbance as that of the Krakatoa explosion might also be fruitful. 



ON IMPACT TESTS. 17 

Impact Tests. — Report of the Committee, consistiufi of Professor 
W. H. Wahren (Chairman), Mr. J. Vicars (Secretary), Professor 
Payne, and Mr. E. H. Saniter, appointed to consider and report 
on the Standardisation of Impact Tests. 

Impact Tests of Materials. 

It is considered that ordinary static tests, such as the tension test on 
standard bars or the cold bending test, do not reveal the capacity of the 
material to resist shocks. In rails, axles, t}Tres and drawbars, armour 
plates, ordnance, moving parts in engines and machinery, the stresses 
are all more or less suddenly applied. It has long been recognised that 
the ordinary static tests in such cases should be supplemented by impact 
tests. Again, Mr. C. Fremont has recently shown that impact tests on 
wire and wire ropes reveal the weakness and want of homogeneity in 
the material in a much more satisfactory manner than static tests. Numer 
ous examples could be quoted where normal .static tests have failed to 
express or define in a satisfactory manner the resistance of material to 
suddenly applied loads. The ordinary tension test may give a reasonable 
strength per square inch, and a reasonable percentage of elongation ; 
but the same material, when subject to impact, may break without much 
deformation and reveal a coarse fracture. Impact tests reveal the brittle- 
ness of the material or its tendency to fail by suddenly applied loads. 
Resilience is a function which is the reverse of brittleness, and expresses 
definitely the resistance to impact. It represents two factors, one of 
which is elongation, and the other the stresses producing them. A metal 
that shows a fair resilience will always give a fair elongation in a state of 
tension, but the converse is not true, as will be shown by the results of 
tension tests and impact tests of a certain steel used for the manufacture 
of high explosive shells. 

The tensile strength per square inch of a steel bar tested in the ordinary 
way is not a true expression of the actual strength, or resistance to break- 
ing expressed as ' tenacity,' because, at the moment of fracture, the area 
contracts locally, and it is this contracted area which breaks. Again, 
this contracted area does not vary with the strength exactly, but depends 
also upon other qualities of the material. 

The hardness number, as determined by the penetration of a steel 
ball orasteel cone — represents more exactly the actual strength or tenacity 
of the material. The Brinell hardness number denoted by A i^i related 
to the ordinary tensile strength per square inch denoted by a- thus : — 

where C is approximately constant for steels of the san^e kind ; thus, 
for structural steel having a tensile strength of 267 tons per square inch, 

A = 143-9 and C = 0186. 

The relation between impact and hardness tests has not been exten- 
sively studied, but it will be shown that there is an approximate ratio 
somewhat similar to that observed in impact and tension tests. 

In regard to experiments made by impact machines on plain and 
nicked pieces, in every case the effect of nicking or notching a bar is to 
bring out more decidedly the properties which we have termed brittleness, or 
want of resilience, and it is this test we propose to more especially consider. 



18 REPORTS ON THE STATE OF SCIENCE. — 1918. 

In order that impact tests on notched bars should be strictly com- 
parable, it is necessary to consider the form and dimensions of the test- 
pieces, the apparatus used in testing them, and the method of record 
and measurement. 

In regard to the form and dimensions of the test-pieces : — 

In tension tests it is clear that the sizes of the test-pieces cannot be 
constant, but the proportions have been established on the law of simi- 
larity which ensures that the test-pieces of different dimensions should 
be geometrically similar in order that the results obtained may be strictly 
comparable. 

Experience with impact on notched bars shows that the resilience 
referred to the area of the cross-section through the notch, when made 
on pieces 10 by 10 mm. and pieces 30 by 30 mm., are not strictly com- 
parable, as the results obtained by the large piece are uniformly greater 
than those obtained with the smaller test-piece, and the difference is 
greater the greater the resilience of the materials. The reason for this 
difference appears to be due to the fact that in the rupture of a notched 
bar we have two distinct stages in the process : (1) the general deforma- 
tion of the bar, which Is proportional to the cube of the homologous dimen- 
sions ; and (2) the rupture of the piece through the notch, which is pro- 
portional to the square of the said dimensions. 

The work of rupture should then be expressed by two terms — the 
work of deforrnation proportional to the cube, and the work of rupture 
without deformation proportional to the square or the area of the cross - 
section through the notch. Professor Schiile has recommended that 
the faces of the test-jjieces on opposite sides at right angles to the 
length of the notch should be polished, and the volume of the piece 
strained in impact, shown by the dull surface, should be used in express- 
ing the resilience. 

The tests made by the authors show that in the brittle shell steel 
there was very little deformation, and the resilience is well expressed 
by the area of the cross-section through the notch, whereas in the case 
of the alloy steels the deformation was considerable, and was not 
confined to the area of the cross-section, but extended to some extent 
on each side of the notch. The method expresses with less accuracy 
the resilience of the more resilient material than that of the brittle or 
less resilient material when expressed in terms of the area through the 
notch, and relatively under-estimates the more resilient material. It 
should be noted that similarity in the form of the test-pieces should be also 
provided in the radius of the notch, and that of the supporting knife-edges. 

Test-pieces. — For notched bar test-pieces, two standard forms have 
been recommended by the International Association for Testing Materials 
(see figs. 1 to 6). 

A small test-piece, 60 mm. long by 10 by 10 mm. in cross-section, 
haying a notch 2| mm. deep, rounded at the bottom to a radius of 1 mm.' 
This is easily jDrepared with a twist drill or a properly shaped milling 
cutter. A larger test-piece, 160 mm. long by 30 by 30 mm. in cross- 
section, having a circular notch 15 mm. deep, formed with a twist drill 

' The dimensions given are not exactly those recommended, but are those actually 
employed in the tests made by the Committee. The recommended depth of notch 
is .5 mm. and the bottom radius s mm. 



ON IMPACT TESTS. 



19 



160 m m 



Q4mm dia drilled "^ 
& rhymed exactly i 



I 




I20m.m ^ 

Fig I 

160mm ^ 



Scale Hair Size 



4mm dia drilled , 
O Vrhymed exactly t 



170 



Fig. 2 . 
60 ^ 



2 mm dia 



SI ik_ 



h-IO^I 



K- -20->l 



•n 



m 



Hair Size 



Half Size 



Fig 3. 



^-::- 


— no mm ^ 

_ 100 - -i_ _ -^ 1 


^ 

7 






o 




T 


n 



240 



Fig. 4- 



'A Size 



2'/j" 



■ 



J_ 



?)■■/. Ji- W — H 



Hii 



4!'s 

Charpy Tension Piece 



Fig 5 



Hair Size 



44mm - - ^ 



^m 



Fig 7 



JL. 



— 40 - 



Detail of Anvil 



TC" 1 

(^2 mm.rad 



r 



for Guillery Machine 





_W " '^ Detail of Tup for Drop-hammer 



20 REPORTS ON THE STATE OF SCIENCE. — 1918. 

and rhymer to a radius of 2 mm., the material betvreen the hole and the 
l»ottom being cut awaj' with a saw. 

An intermediate size has been proi)osed and used extensively, and 
the authors have adopted it as w-eU as the two former sizes ; it is 160 mm. 
long by 20 by 20 mm. in cross-section, with a similar notch to the 30 by 
30 mm. piece, but only 5 mm. deep. 

In addition to notched bar tests tlie authors have made tension tests 
on specimens without notches. 

(a) J in. diameter and 2| in. gauge length, broken with a single blow 
iu a small Charpy machine. 

{b) 10 mm. diameter and 100 mm. gauge length, broken with a series 
of blows in a Martens drop-hammer machine. 

The advantage of the circular notch over the acute triangular notch 
is that it can be made and reproduced accurately in a regular manner, 
so that the conditions of the test in so far as the notch is concerned are 
kept as constant as possible. 

The disadvantage is that more energy is consumed during the period 
when the bar undergoes deformation, before a crack is developed at the 
notch, than occurs with the acute triangular notch. The resilience ex- 
pressed in regard to the area of the cross-section through the notch is 
greater with circular than with triangular notches, and increases with 
the radius of the circular notch. At the same time the relative results 
obtained in grading material with circular or triangular notches do not 
vary to any great extent. If, however, the work done diiring the two 
periods of deformation and fracture could be separated and accurately 
determined, the triangular notch would undoubtedly supersede the 
circular notch, as the results of the test referred to the area of the cross- 
section through the notch would more accurately express the resilience. 

As to the advantages of the small test-pieces, 10 by 10 mm., over 
the larger, 30 by 30 mm. : — A larger number of pieces can be obtained 
from a given piece of material, and local defects more clearly exposed. 
Agiin, the selection of the test-pieces after a microscopic examination 
of a suitably prepared and etched surface revealing any heterogeneity 
is more completely accomplished with the smaller test-pieces. The 
larger test-pieces enclose more or less any local defects, and it is not so 
easy or convenient to obtain sufficient specimens. 

The smaller test-piece can be broken in a smaller machine. 

Impact-testing Machines.- — All impact-testing machines should be 
designed in such a manner that the actual energy required to fracture 
the test-piece in one blow may be accurately determined. They should 
be calibrated from time to time, and the losses of energy due to friction 
and other causes should be accurately determined. The machines should 
be kept in good order and handled carefully. The machines used in the 
various tests made by the authors are sufficiently known, so that a detailed 
description is unnecessary, but it may be necessary to state the following 
particulars : — 

A. The Guillery Machine. — This machine consists of a fly-wheel 
21 in. diameter, carrying a knife with striking edge 2 mm. radius. 

The knife-edges supporting the test-piece are spaced 40 mm. apart, 
and are rounded to 2 mm. radius. {Vide Fig. 7.) 

The maximum velocity of impact is equivalent to a fall of 4"8 metres 
and the corresponding energy is 60 kilogrammetres. (K.G.M.) 



ON IMPACT TESTS. 



21 



The recording device consists of a centrifugal pump driven from the 
main axis and supplying a column of water in a glass tube, the height 
of which is proportional to the velocity of the wheel. A scale attached 
to the tube shows the number of revolutions and K.G.M. at any instant, 
and the drop in the water column after impact shows at a glance the 
K.G.M. absorbed by the fractiu-e of the test-piece. The error is due 
to the energy lost by the release of the catch just before impact, and 
amounted to 0-8 K.G.M. The machine is only suitable for the 60 by 10 
by 10 mm. notched bar test, and is more satisfactory for resilient than 
for non-re.silient .steel, as the former causes a greater depression of the 
water column. The machine is operated by hand through friction gearing. 

B. The Charpy Pendulum Hammer. — These are made in three sizes, 
but the one used by the authors has a maximum capacity of 32 K.G.M. 
and a maximum fall of 142 metres ; the striking edge of the pendulum 
is 2 mm. radius; the supports are spaced 40 mm. apart and are not rounded. 
This machine is arranged to test the 60 by 10 by 10 mm. notched bar, 
but it can also test a tension-piece with or without notches, and record 
the energy required to break it in a single blow. The usual size of the 
test-piece is j in. in diameter, with screwed ends, and a gauge length of 
2J in. The arrangement for tension tests has been modified and con- 
siderably improved by one of the authors. 

The CJiarpy Pendulum. 
Method of determining Energy of Rupttire. 




Fig. 8. 



To obtain the energy absorbed in the ruptm-e of the test-piece, multiply 
the difference of height of the centres of gravity of the pendulum at the 



22 REPORTS ON THE STATE OF SCIENCE. — VMS. 

beginning and end of the swing by the weight of the hammer. This 
result must be corrected for friction. (Fig. 8.) 

Let OA = Initial position of pendulum. 
OC = Position after free swing. 
OC = „ ,, second free swing. 
OB = ,, ,, rupture of test-piece. 
OB' = ,, ,, first swing after rupture of test-piece. 
K = Energy of rupture. W = weight of hammer. 

Then— 

K = (Energy just before impact) — (Energy just after impact). 
= (W/?a — friction loss over z. AOX ) 

— (Wh' + fi-iction over z XOB) 

But friction loss over /^ AOX = ^ friction loss over z. AOC 

= I Wo. 

Similarly friction loss over /i XOB = J W6. 
.-. K = [Wka - iWa) - (W/i' + i W6). 
= (Wh - W^') + (- iWa -} - Wb) 
but h^ = h + la 

.-. K = W (/*"- ;*') + iW (a - b). 

a = I (cos zCOY - Cos zC'OY) : b = l (cos zB'OX - Cos z BOX) 

where I = length of pendulum from suspension to the centre of gravity. 
By observing the decrement in the swing we may find values of a 
and b, and hence of \W {a — b) for any value of a. Tabulate these values 
and plot z. BOX against the friction correction k'. 

K = W {h — ¥) + k' 

= Wl cos a — WZ cos a, -I- k'. 

The Direct Fall or Block Hammer. 

The type used in these tests was designed by Martens, but a recording 
drum apparatus has been added, made by Messrs. Amsler. Various 
hammers can be used in this apparatus, but the authors, after much 
experimenting, decided to use a 36 K.G-. for the more resilient steels, 
and a 12 K.G. hammer for the less resilient shell steel. The height of 
drop was 3 metres in each case. 

The hammer has a striking face with the sides inclined at 50", and 
the ends rounded to a radius of 2 mm. The test-pieces are supported 
on specially designed steel castings, with edges rounded to a radius of 
2 mm. and spaced 120 mm. apart in order to suit the 160 by 30 by 30 mm., 
and the 160 by 20 by 20 mm. test-pieces. The weights of the anvil are 
as follows : — 

Steel castings 90 lb. 

Cast-iron anvil to which the castings are bolted 2,300 „ 
Concrete foundations on shale rock . . . 7,600 „ 



Total weight 9,990 lb. 



ON IMPACT TESTS. 28 

Ratio of weight of hammers to anvil and foundations 1 : 277 and 
1 : 832 respectively, so that, as far as rigidity of the anvil is concerned, 
the effect of the blows of the hammer would be as severe as possible 
vmder the circumstances, and the results woiild be much less than with 
an anvil on springs or timber. 

The recording apparatus for determining the energy of rupture con- 
sists of a drum rotated at a constant speed by means of an electric motor. 
A style attached to the falling hammer describes a diagram on the drum 
showing the velocities of the tup just before and after impact. The 
apparatus can be attached to the frame of the machine and adjiisted 
to suit the heights required for various tests. 

In order to determine the losses of energy due to the friction of the 
hammer on the guides of the machine, and also that due to the deforma- 
tion of the hammer and the frame, we may proceed in the following 
manner : — 

First, calibrate a strong spring, such as a triple carriage-spring, in a 
static compression-machine by obtaining a diagram of the loads and 
corresponding deformations. The area of the diagram up to any given 
deformation gives the work done or energy corresponding with this de- 
formation. Place the spring on the anvil of the impact machine and 
determine the deformations due to various heights of drop, and find 
the ratio of the height corresponding with the deformation of the spring 
to the actual height of the fall. If h = actual height, and /i|= the height 
corresponding with the energy represented by the deformation of the 
spring, and n the ratio of /;, to h, then — 

h 
and the energy = n W/i. 

It shoidd be noted, however, that we here assume that the work 
done in compressing a spring a definite amount is the same whether 
the load is applied steadily or by impact. This assumption is probably 
incorrect. 

Copper crusher gauges may be used instead of or as a check on the 
spring. 

Mr. P. Welikhow, of Moscow, in order to show the relationship between 
the ordinary static tension tests and impact tension tests, used an impact 
machine precisely the same as that used by the authors, and, by means 
of a calibrated spring, determined the value of the energy due to a given 
fall, then placing a standard tension test-piece in the shackles of the 
machine resting upon a weaker calibrated spring, and noting the com- 
pression of this spring representing the kinetic energy remaining in the 
hammer after rupture of the test-piece. The energy required to break 
the test-piece was clearly the energy of the hammer found by the first 
test on the triple spring, less the work absorbed by the second spring. 

All the conditions are practically identical in the two cases. The 
friction against the guides is exactly the same, the losses due to the de- 
formation of the hammer, and the frame carrying the test-piece are the 
same in both cases, so that the fracture of the test-piece alone diminishes 
the work absorbed by the spring. Three kinds of steel were tested in 
tension by impact and by ordinary static tension, soft cast-steel, hard 



n = '- ' 



24 



KEPORTS ON THE STATE OF SCIENCK. — 1918. 



cast-steel, and extra hard cast-steel . The area of the stress-strain diagrams 
obtained in the static tension machine were determined. Thus, if P = 
the breaking load, T = the energy of rupture, AZ = the total elongation, 
and a the diagram factor, then : — 

T=aPA/ and P= -^,. 

The test-pieces had a length of 110 mm. and a diameter of 10 mm. 
The results are shown in the following Table I. : — 



Table I. 



— 








: Static tests 


Impact tests 
3040 


Soft Steel. 


Breaking load . 


3050 




Elongation 






i 31% 


32% 




Contraction 






1 63% 


60% 


Hard Steel 


Breaking load 






5240 


4750 




Elongation 






i 20% 


20% 




Contraction 






43% 


48% 


Extra Hard Steel . 


Breaking load 






6630 


6930 




Elongation 






o /o 


11% 




Contraction 


0*J0/ 

-«' ,o 


24% 



The results show that impact tension tests not only supplement the 
static tension tests by giving the kinetic strength of the material, but 
in certain cases can replace it as it gives all the characteristic values of 
the properties of the material, excepting the elastic limit. It should 
be noted, however, that the relatively massive frame forming the tension 
shackles in the Martens machine absorbs a large portion of the energy 
of the hammer at the moment of striking. Impact tests on steels in 
tension, in which a triangular or circular notch has been cut, give results 
similar to those obtained in static tension after local extension has com- 
menced. Impact tension tests do not reveal the brittleness of the material 
like the notched bar tests. In regard to the determination of losses in 
the direct fall machine, we have adopted the following method : — 



MARTENS' DROP HAMMER. 

Method of determining the Energy of Rupture. 

The energy of rupture is obtained by determining the energy of the 
tup just previous to and just after the impact, and taking the difference. 
Thus if hi =equivalent height for veloc. before impact, 
^2= ,, ,, ,, „ after 

W=weight of tup, 

K=energy absorbed in rupturing test-piece, 
then K=W (/t, -/i.,). 

h\ and /«2 ^^rc determined by taking an autographic diagram on a 
revolving drum, and simultan(^ously recording the velocity of the driun 
by means of a chronograph. 



ON IMPACT TESTS. 



25 



A small style attached to the tup describes a curve on the drum as 
shown below : — 




The velocity of the tup before and after impact is t)i=Vtanaand 
y2=V tan )8 
where V is the velocity of the drum. 

Connection is made to a chronograph, controlled from the testing 
laboratory, which indicates revolutions of the drum and J seconds, thus 
fixing V. 

We can therefore either calibrate the apparatus for any given hammer 
and height of fall, by dro^jping the tup without the insertion of the test- 
piece and calculating the per cent, loss of energy, or we can determine 
the actual loss for every test. The former method would be used for 
ordinary commercial testing, as the latter involves the use of a chronograph 
for every test. 

The former was used for Rll R19 R31 and 5960 steels, and the more 
accurate method for 3198 3184 2300 1324 and the gun steels. 

When the chronograph is not employed, the method of calculation 
is as follows : — 

Veloc. at A is v,=V tan a and at B is 1^2= V tan fi 

ii Ag V\ V\ 

But ^^=*^ /. k,-h.,=h, {1-f^). 
V\^ tan^ a tan^a 

The energy of rupture is therefore n Wh ( 1— +^"2 ) + W/j' 1, 

where 7i' is the height between the zero line and point A and n is a 
constant less than unity determined by calibration of the machine as 
above. 

The height 7i] calculated in this manner is always less than the 
actual height h, and the difference /i— /i, due to frictional losses is greater 
as the weight of the hammer decreases. Let the weight of the hammer 

be 12 kilos. If sp = the speed of the drum in feet per sec. = 11-6 '^"'^''^ 

the velocity of the hammer at the moment of impact is :— 

„ 11.6 n.Tr.(l , „ 1 • n 
sp. tan (3= 12x60 ' /^='*-*i ^^^ P- 



12x60 



20 REPORTS ON THE STATE OF SCIENCE.— 1918. 

;i.,='illll^^^=-0007377 n^ tan^ B feet. 

= •0002249 vi2 tan- (3 metres 

Fi'om a chronograph record, n=-13d'5 and from the diagram 

, r> 3-43 J -0002249 X 139-52 X 3-432 

tan^=— - ;j2 = j;295 =2-797 metres 

The loss is represented by 7i—/i.2=3— 2-797 = 0-203 metres. 
In this case the loss due to friction is 6-8 per cent. 

After impact measure from diagram tan y8=— ^^, and then 

-0002249 X 139-52 ^ 5.302 



-=2-480 metres 



7-042 

Therefore the loss due to rupture of test-piece is 
2-797-2-480=0-317 metres. 
If W=12 kilos the total energy absorbed in rupture= 
12x0-317=3-804 K.G.M. 

The frictional losses with the 36 kilo hammer were 1-8 per cent. 

Remarks on Impact-Testing 3Iachines. 

The Charpy pendulum hammer is a very suitable machine for testing 
brittle materials, as the swing of the pendulum after impact is greater 
than with less brittle materials. The Guillery machine is a very suitable 
machine for testing tough materials, as the water column descends to a 
greater extent than with less tough materials. 

In both machines the energy of the moving masses at the moment 
of impact is expended in causing the rupture of the test-piece, and in 
producing deformations of the frame of the machine and the anvil, the 
remaining energy in the moving masses is shown by the angle moved 
through by the pendulum, and the fall of the water column in the Charpy 
and Guillery machines respectively. The errors due to the deformations 
of the frame and anvil cannot be easily calculated. If we have a pendulum 
anvil as well as a pendulum hammer, we can find the actual energy 
absorbed by the test-piece, after determining the losses due to friction. 
If the masses representing the pendulimi anvil are about twenty times 
the mass of the pendulum hammer, such a machine would give results 
of comparative value which could be used in expressing definitely the 
resilience of the material. Dr. Stanton found that with a pendulum 
anvil the energy of rupture was 5 per cent, lower than in a simUar machine 
with a fixed anvil. 

In the direct fall machine such as the one used by the authors, pro- 
vided with the apparatus for the determination of the energy of the 
hammer at the moment of and immediately after impact, the difference 
between these energies is not entirely expended in the rupture of the 
test-piece, but the losses due to deformations of the hammer and anvil 
are relatively small, and, when carefully used, this machine will give 



ON IMPACT TESTS. 



27 



satisfactory results. If the anvil is supported on springs the results 
would compare more or less with the double pendulum, but the com- 
pression of the springs could not be determined as accurately as the move- 
ment of the pendulum anvil. 

To standardise the impact test, it would be desirable to agree as to 
the magnitude of the moving masses and the type of machine, as the 
blow would be much sharper in the direct fall machine in consequence of 
its more massive anvil, and in specifj'ing the resilience it is necessary 
to assume that all the conditions affecting the results should be maintained 
practically constant. 

In connection with the notched bar tests made by the authors, the 
angle of rupture was measured after fracture (fig. 8). It is only possible 
to do this accurately when there is contact over the whole surface. In 
the tougher materials there is considerable sliding of the surfaces, 
one may be convex and the other concave. Again, in some of the larger 
pieces, both parts were convex. If the angles are plotted against energy 
of rupture, it will be found that a relationship exists : — 

Energy of rupture per sq. cm. K 

Angle of rupture D 

In the various tables of results it will be seen that this ratio is more 
or less constant, and any difference is largely due to the difficidty in 
correctly measuring the angle of rupture. 

Mesnager found that for the smaller test-pieces K=0-375 D, and for 
the larger test-pieces K=l-fO-58 D. 

He also found that if R denoted the tensile strength of the material 
in kilogrammes per sq. cm., then : — 

For the small pieces :— R-f-2-66 D=95, 
„ „ larger „ R-fr72 D=87. 

A similar relationship could be established between the angle of 
rupture and hardness by plotting a sufficient number of tests, but all 
such equations would be more or less approximate, and in the case of 
brittle steels the angle is too small to measure and the method fails entirely. 

The steels tested by the authors have the following composition : — 

Table II. 
Chemical Aiuilysis. 



Mark 



Rll 

R19 

R31 

.5960 

3198 

1324 

2300 

3184 



C 



•29 
•25 
•30 
•22 
•44 
43 
•50 
•45 



,^1 



•083 
•108 
•121 
•140 
•12 
13 
•13 
•074 



s 


P 


Mn 


■027 


■024 


! 

•48 


038 


•031 


•71 


•027 


•028 


■65 


032 


•028 


•50 


•014 


Trace 


•87 


023 


•008 


•83 


■024 


•015 


•68 


•019 


•012 


•72 ; 



Cr 



•56 



•81 



Ni 



/o 
2-88 
3-27 



28 REPORTS ON THE STATE OF SCIENCE. — 1918. 



Conclusions on Results. 

The results of the small notched-bar tests on the Charpy and Guillery 
machines are given in Tables VII. to VIII., and those obtained with 
Martens' direct-fall machine are given in Tables IX. to XII. 

The shell steels are much less homogeneous in quality than the other 
steels and have a very low resilience. Again, the angle of rupture was 
too small to be measured accurately. 

With the small test-pieces the energy required to produce rupture 
was approximately the same in both the Guillery and the Charpy machines, 
but the former was more severe upon the steels denoted by Ell, R19; 
and the gun steel than the latter. 

In the direct-fall machine on the larger test-pieces, the energy required 
to produce rupture was less for the brittle shell steels, and greater for 
the steels denoted by Rll, R19, and the gun steel. The brittle shell 
steels tested would naturally give low results owing to the severity of 
the blow on the more rigid anvil, but this did not affect to the same 
extent the three other steels, and the higher results are due to the larger 
test-pieces, and correspond more or less with similar results obtained 
by Mesnager and others on large and small test-pieces. 

The results are shown more clearly in the Summary 1, Table III., but 
for the carbon steel R31 and the vanadium chrome steel, 5960, the results 
are irregular, the latter being highest in the Guillery machine, K.G.M. 
=13.11, and only about one-third of this in the direct-fall machine. 
In regard to the ratio of the energy of rupture per sq. cm. to the angle 
of rupture, Summary 2, Table IV., it appears that the values given for 
various steels are so variable that the method cannot be considered as 
anything more than a rough approximation, and the equations derived 
by Mesnager can only apply to the particular steels included in his 
experiments. 

The hardness numbers obtained by the Amsler cone given in Summary 
3, Table V., show that the material in the small and large test-pieces was 
not exactly the same, and these differences would affect the results of 
the notched-bar tests to a corresponding extent, if the differences were 
due entirely to hardness, but the spread under the punch in the smaller 
test-piece may account to some extent for the smaller hardness number 
obtained. It is clear, however, from the nature of these tests, and the 
difficulty of keeping all the conditions affecting them constant, that 
impact tests on notched bars cannot be expected to give results comparable 
in regularity with those obtained in the ordinary static tension tests ; 
at the same time they reveal in a striking manner the brittleness of the 
material. The results obtained by static tension and impact tension on 
the small test-pieces used in the Charpy machine corroborate those 
obtained by Mr. P. Welikhow in so far as they show that impact tension 
tests give results comparable with static tension tests, but Tables XIII. 
and XIV. show that the energy of rupture is greater in the impact tests 
than in the static tests, also that the elongations and contractions of 
area of fracture do not differ to any considerable extent. The closer 
agreement obtained by Welikhow is due to the larger amount of energy 
absorbed in the tension shackle of the direct-fall machine used by him, 
and the closer approximation to the conditions of the ordinary static 



ON IMPACT TESTS. 29 

test. The brittle shell steels gave excellent results in both the static 
and the impact tests, and there was nothing to suggest brittleness excepting 
the coarse crystalline fractures which occurred in two of the heats. Again, 
in the case of the other steels, there was nothing to suggest their resilience 
and toughness excepting their larger contractions of area of rupture, 
and their fine silky fractures. In regard to the impact tension tests in 
the direct-faU machine on standard test-pieces with a series of blows from 
hammer of 12, 18, and 36 kg., and falls of 2 and 3m., it should be 
remembered that, although the anvil was very rigid, the tension shackle 
would, in consequence of its large mass relative to that of the test-piece, 
reduce considerably the severity of the impact, and the number of blows 
in each case necessary to produce rupture would be a measure of the 
endurance of the material. The elongation per blow decreases at first, 
then remains constant even after the test-piece has begun to neck slightly, 
and then increases near the last blow to about its initial value. The 
material is modified by the first blow and a hardening effect produced. 
Tables XV. to XVII. and Summary 4, Table VI., give the results of these 
tests, from which it wiU be seen that the relative values of the results vary 
with the weight of the hammer and the drop. 

We consider that satisfactory impact tests can be made by means 
of the Charpy or the Guillery machines and that the smaller test-piece 
60 by 10 by 10 mm. is preferable to the larger 160 by 30 by 30 mm., as 
the former is better adapted for revealing local defects, and can be broken 
with a smaller machine. Test-pieces may be cut out of the portions of 
the material where local defects appear to exist, and these are suggested 
by the appearance of the polished surface after etching. 

It does not appear to be necessary to substitute a pendulum anvil 
for the ordinary fixed anvil. 

There does not appear to be any definite relationship between different 
kinds of materials connecting the impact test properties with the static 
tension test properties. The effect on the material being different in the 
two tests seems to indicate that a standard impact test should be laid 
down by the British Standards Committee as well as the standard tensile 
test. 

The extended use of steel for utility purposes seems to point to the 
suggestion being an vu'gent one. 



1918. 



3a 



EEPORTS ON THE STATE OF SCIENCE. — ^1918. 



Table III. 

Summary 1. 
Energy of Rupture, 

K.G.M. per sq. cm. at notch. 





Guillery 


Charpy 


Martens' Drop Hammer 




Mark 










Remarks 


10x10 


10x10 


20x20 


30x30 


3198 


1-49 


111 


•68 


•87 


Carbon Steel 


2300 


2-49 


1-22 


•87 


1^09 


»> s> 


1324 


2 02 


1-85 


104 


•96 


>J- s> 


*1324 


1-68 


118 


•86 


•85 




3184 


217 


1-49 


1-08 


119 


?J >> 


Gun Steel 


9 80 


10-85 


15-09 


11-33 




B31 


10-71 


10-58 


11-43 


2-45 


Carbon Steel 


5960 


1311 


10-66 


4-24 


351 


Vanadium Chrome 


RU 


8-54 


14-24 


2016 


17-68 


Nickel Chrome 


R19 


5-91 


12-84 


20-11 


1610 


Nickel Steel 



* These figures are a mean of 1324 Al 
gave exceptionally high results throughout. 



A7 A14, i.e., neglecting A20 which 



i 



Table IV. 



Summary 2. 



P ,. E nergy of rupture per sq. cin. ^K 
' Angle of rupture D 





Guillery 


Charpy 


Drop Hammer 




Mark 








Remarks 


10x10 

oo 


10x10 


i.20x20 30x30 




3198 


oo 


oo 


oo 


Carbon Steel 


2300 


oo 


oo 


oo 


oo 


ff ?> 


1324 


oo 


oo 


oo 


oo 


9> J» 


3184 


oo 


oo 


oo 


oo 


39 >> 


Gun Steel 


•692 


-639 


•851 


•734 




R31 


•466 


•474 


•564 


•990 


Carbon Steel 


6960 


•509 


•525 


•756 


-781 


Vanadium Chrome 


Rll 


-217 


•369 


•865 


•907 


Nickel Chrome 


R19 


•326 


-647 


-696 


•841 


Nickel Steel 



ON IMPACT TEST?, 



31 



Mark 



Table V. 

Summary 3, 
Hardness by the Amsler Cone 



3198 
2300 
1324 
3184 
Gun Steel 
R31 
5960 
Rll 
R19 



Guillery 


Charpy 


Drop Hammer 


10x10 


10x10 


20x20 


30x30 ! 

1 


172 


168 


178 


200 


194-5 


191 


201 


201 


198 


187 


196 


209-5 


173 


178 


187 


195 


289 


282 


246 


231 


125 


121 


154 


153 


221 


220 


218 


239 


148 


146 


225 


200 


226 


213 


245 


206 



Remarks 



Carbon Steel 



Carbon Steel 
Vanadium Chrome 
Nickel Chrome 
Nickel Steel 



Table VI. 

Summary 4. 

Impact Tension. Martens' Drop Hammer; 
Number of Blows required for Rupture. 



Mark 


18 kg. 
2 mts. 


18 kg. 
3 mts. 


36 kg. 
2 mts. 


Remarks 


Gun Steel 
R31 
5960 
Rll 
R19 


135 

11 

11 

16 

11 


8-5 
9-5 
5 
9 

7 


5 
3 

I 


? 
Carbon Steel 
Vanadium Chrome 
Nickel Chrome 
Nickel Steel 



32 



REPORTS ON THE STATE OF SCIENCE. — 1918. 



Table VII. 

Guillery Apparatus. 
Test-piece 10 x 10 x 60. Area at notch 75 sq. cm. 





Energy of rupture 










Mark 






Angle of 
rupture 


K 
D 


Hard- 
ness 


Remarks 


K.G.M. 


K.G.M. 






sq. cm. 














K. 


D° 








3198 Bl 


•7 


•93 





oo 


173 




3198 B9 


1-2 


1-59 





oo 


169 




3198 B17 


1-5 


1-99 





oo 


166 




3198 B24 


11 


1-46 





oo 


181 




2300 Bl 


1-6 


213 





oo 


199 




2300 B7 


1-9 


2-53 





oo 


195 


Fracture : Coarse 


2300 B14 


21 


2-80 


2 


1-400 


194 


crystalline.traces 


2300 B21 


— 


— 


— 


oo 


190 


of fine crystals 


1324 Al 


1-2 


1-59 





oo 


193 


^ at compression 


1324 A7 


1-2 


1-59 





oo 


199 


edge. 


1324 A14 


1-4 


1-86 





oo 


194 




1324 A20 


23 


3 05 





oo 


205 


f Very roHgh and 
1 jagged fract. 


3184 B2 


1-6 


213 





oo 


175 




3184 B9 


1-6 


214 


3 


•713 


178 




3184 B15 


2-2 


2-93 


5 


•586 


167 




3184 B26 


11 


1-47 





oo 


171 




Gun Steel 2 
j> j» 4 
,> >> 6 


8-9 
9-2 
6-6 


11-66 
911 
8-64 


15 
15 

22 


•777 
•607 
-393 


289 
291 
286 


1 Minutely fine 
1 crystals. 


R31 4 


81 


10-8 


23 


•470 


125 




R31 5 


7-9 


10-53 


23 


-458 


125 


Fine crystals, 


R31 6 


81 


10-8 


23 


•470 


— 


■ minutely fine at 


5960 4 


81 


10-8 


20 


•540 


221 


edges. 


5960 5 


8-2 


10-93 


20 


•546 


221 




5960 6 


132 


17-6 


40 


-442 


248 


Minutely fine 
crystalline. 


Rll 2 


6-4 


8-54 


37 


231 


148 


Fine crystals, 


Rll 3 


6-3 


8-40 


37 


•227 


148 


minutely fine 


Rll 8 


6-5 


8-67 


45-1 


•193 


— 


at edges. 


R19 1 


4-5 


6-00 


27-5 


•218 


221 


1 Miniitelv fine 


R19 4 
R19 5 


4-4 
4-4 


5-87 
5-87 


13-5 


•435 


009 L •^ 

236 ) '''ystaiiii^^^ 



i 



ON IMPACT TESTS. 



33 



Table VIII. 

Charpy Apparatus. 
Test-piece 10 x 10 x 60. Area at notcli "75 sq. cm. 







Energy 


[rupture 


i 








Mark 






Angle of 
rupture 


K 
D 


Hard- 
ness 


Remarlia 


K.G.M. 


K.G.M. 








sq. cm. 






i 










K 


D° 








3198 


Bl 


•85 


113 





CO 


173 




3198 


B9 


•86 


114 





oo 


161 




3198 


B17 


•80 


106 





oo 


163 




3198 


B24 


•83 


110 





oo 


174 




2300 


Bl 


•78 


104 





oo 


184 




2300 


B7 


103 


137 





oo 


190 


Coarse crystalline 


2300 


B14 


•96 


1-28 





oo 


191 


fracture, fine 


2300 


B21 


•90 


119 





oo 


199 


crystals at ex- 


1324 


Al 


105 


1-40 


5 


-280 


197 


/ treme compres. 


1324 


A7 . 


•85 


113 





oo 


182 


eion edge._^^ 


1324 


A14 


■75 


100 





oo 


190 


, 


1324 


A20 


2-92 


3-88 


8 


-485 


180 { 


1324 A20 
Finer crystals. 


3184 


B2 


1-25 


1-66 





oo 


178 




3184 


B9 


1-23 


163 


2 


•815 


175 




3184 


B15 


105 


1-40 


1 


1 40 


194 




3184 


B26 


•96 


128 


3 


■427 


165 


^ 


Gun Steel 1 


8.38 


10-94 


18 


-607 


284 


Minutely fine 


ty 


„3 


8-25 


10-80 


16 


-674 


284 


cryst. Silky at 




,.5 


817 


10-82 


17 


•637 


277 


edges. 


R31 


1 


812 


10-83 


23 


•473 


120 


1 Fine cryst.. 


R31 


2 


7-84 


10-45 


22 


•475 


120 


( minutely fine 
' at edges. 


R31 


3 


7^84 


10-45 


22 


•475 


123 


5960 


1 


812 


10-83 


21 


•517 


220 


[Fine cryst.. 


5960 


2 


802 


10-69 


20 


•535 


218 


minutely fine 


5960 


3 


7^84 


10-45 


20 


■523 


222 


at edges. 


RU 


7 


1057 


1410 


38-6 


•365 


151 


Fine crystal, 


Rll 


10 


1100 


14-67 


37 5 


•391 


142 


minutely fine 


RU 


11 


1045 


13-95 


37-7 


-352 


145 


at edges. 


R19 
R19 


6 
9 


1217 
9 06 


i 16-24 
! 12-08 


27-0 
27-5 


•610 
•441 


206 
214 


Minutely fine 
crystalline. 


R19 


12 


7-68 


■ 1021 


17-3 


•590 


218 



34 



REPORTS ON THE STATE OF SCIENCE. — ^1918. 



Table IX, — Martens' Drop Hammer. 

Weight of tup 36 kg. Height of fall 3 mts. 
Test-piece 20 x 20 x 160. Area at notch 3 sq. cms. approx. 



Mark 



Gun Steel 7 
»> }> 8 

„ „ 10 
R31 1 
R31 2 
R31 3 
R31 4 
5960 1 
5960 2 
5960 3 



Rll 
Rll 
Rll 
R19 
R19 
R19 



Energyof rupture 










Angle of 
rupture 


K 


K.G.M. 


K.G.M. 

sq. cm. 


D 




K 


47 02 


15-58 


18 


-866 


44-47 


14-82 


17 


-872 


4602 


1531 


19 


•805 


44-43 


14-64 


17 


-861 


37-68 


1256 


19 
20 
20 


-661 


28-56 


9-52 


-476 


36-60 


12-20 


22 


-555 


13-80 


;4-60 


7 


•657 


17-28 


5-76 


7 


-823 


7-08 


236 


3 


•787 


6312 


21-04 


24 


•877 


63-72 


21-24 


25 


•850 


54-60 


18-20 


21 


•867 


60-84 


20-28 


28 


•724 


62-52 


20-84 


38 


•548 


57-60 


19-20 


23 


•817 



Hard- 
ness 



248 
244 
259 
232 
151 
161 
152 
157 
217 
218 
220 
231 
227 
216 
240 
261 
230 



Remarks 



Fine crystalline, 
(- minutely fine 
J at the edges. 



-Fine crystalline. 



Minutely fine 
crystalline with 

- deep cracks. 
R19 " Horn 
type " fracture. 



Table X. — Martens' Drop Hammer. 

Weight of tup 36 kg. Height of fall 3 mts. 
Test-piece 30x30x160. Area at notch 4.5 sq. cms. approx. 



Mark 


Energy of rupture 


Angle of 
rupture 


K 
D 


Hard- 
ness 


Remarks 

Fine crystalline, 
minutely fine 
at edges. 

■Fine crystalline. 

Minutely fine 
crystalline with 
deep cracks. 
R 19-1 Fine 

■ crystalline with 
minutely fine 
crystals at 
edge. 


K.G.M. 


K.G.M. 
sq. cm. 


Gun Steel 11 
» » 12 

3> >J 13 

» „ 14 

R31 5 

R31 6 

R31 7 

R31 8 
' 5960 5 
, 5960 6 

5960 7 

5960 8 

Rll 1 
i Rll 2 
\ Rll 3 
1 Rll 4 

R19 1 
I R19 2 

R19 3 

R19 4 


4659 
5274 
5964 
4605 
13-68 - 

918 
10-26 
2484 

972 
1530 
1332 
79-56 
85-14 
7686 
75-78 
53-64 
77-76 
7830 
8010 


K 
1034 
1161 
1316 
1019 

3-04 

2 04 
2-28 
5-52 
216 

3 40 
296 

17-68 
18-92 
17-08 
16-84 
11-92 
17-28 
17-40 
17-80 


16 
17 
15 
14 

3 
25 
25 

2 

5 
95 

3 
4-5 
20 
22 
18 
18 
17 
16 
20 
25 


•646 
•683 
•877 
•728 
1013 

■816 

114 

1104 

-227 

1133 

-658 

-884 

•860 

•949 

•936 

•701 

1080 

•870 

•712 


230 

230 

240 

224 

170 

152 

142 

149 

243 

240 

235 

237 

201 

194 

197 j 

210 

158 

207 

207 

205 



ON IMPACT TESTS, 



85 



Table XI. — Martens' Drap Hammer. 

Weight of tup 12 kg. Height of fall 3 mts. 
Test piece 20 x 20 x 160. Area at notch '3 sq. cms. approx. 



[ 

1 




Energy of rupture 










Mark 


K.G.M. 


K.C.M. 


Angle of 
rupture 


K 
D 


Hard- 
ness 


Remarks 








eq. cm. 
K 
















D" 








3198 
3198 


Bl 
B9 


2-36 
115 


•79 
■39 






oo 
oo 


169 
180 


1 Tup 36 kg. 


3198 


B17 


1-90 


•63 





oo 


180 


\ 


3198 


B24 


2-66 


•89 





oo 


183 




2300 


Bl 


2-29 


•76 





oo 


202 


' 


2300 


B7 


373 


1-25 





oo 


194 




2300 


B14 


1-88 


•63 





oo 


201 




2300 


B21 


253 


•84 





oo 


208 


Fracture : Coarse 


1324 


Al 


233 


•78 





oo 


194 


\ crystalline. 


1324 


A7 


317 


106 





oo 


194 


3184/B26 finer 


1324 


A14 


2-22 


•74 





oo 


194 


than others. 


1324 


A20 


4-75 


156 





CO 


202 




3184 


B2 


313 


108 





oo 


187 




3184 


B9 


4-62 


163 


2 


•765 


193 




3184 


B15 


2-54 


•86 





oo 


182 




3184 

1 


B26 


2-63 


•84 





oo 


187 


/ 



Table XII. — Martens' Drop Hammer. 

Weight of tup 12 kg. Height of fall 3 mts. 
Test-piece 30 x 30 x 160. Area at notch 45 sq. cms. approx. 





Energy of rupture 










Mark 






Angle of 
rupture 


K 
D 


Hard- 
ness 


Remarks 


K.G.M. 


K.G.M. 






sq. cm. 














K 


D° 








3198 Bl 


— 


— 





oo 


180 


\ 


3198 B9 


3^85 


■85 





oo 


203 




3198 B17 


3-91 


•87 





oo 


206 


' 


3198 B24 


398 


•88 





oo 


210 




2300 Bl 


485 


108 





oo 


201 




2300 B7 


380 


•85 





CO 


198 




2300 B14 


605 


112 





oo 


198 




2300 B21 


584 


129 





oo 


207 


I Fracture : Coarse 


1324 Al 


3 82 


•85 





oo 


201 


[^ crystalline. 


1324 A7 


383 


•84 





CO 


215 




1324 A14 


3-82 


•85 





oo 


213 




1324 A20 


604 


131 





oo 


209 




3184 B2 


637 


141 





oo 


198 




3184 B9 


518 


115 





oo 


196 




3184 B15 


438 


•97 





oo 


198 




3184 B26 


554 


123 


2 


•615 


187 


J 



36 



REPORTS ON THE STATE OF SCIENCE. — 1918. 



Static. 



Table XIII. — Comparison of 
Impact by 





Ultimate 


Elongation 


Con- 




Energy of 






Strength 
Tons 




1 






rupture 
K.G.M. 




Mark 


Gene- 




Total 


tion of 


Fracture 






in.=' 


ral 


Local 


on 2" 


Area 




cb. cm. 








% 


Inch 


% 


% 








Gun Steel ] 


L 5106 


7-5 


•21 


180 


62-6 


Minutely fine crys- 
tals, cup-shaped. 


12^86 




e 


5 48-88 


8-0 


•28 


220 


60-0 


— 


15^05 




Rll I 


5 — 


— ■ 


— 


— 


— ■ 


— 


~~* 




50-83 


4 


■21 


14-5 


62-64 


Minutely fine crys- 


10-33 
















tals, silky at edges. 






2 




i 


_ 


. 1 


_ 


cup-shaped. 







3 

R19 1 

2 


50-55 


6-5 


■25 


18 


61-30 


Ditto 


1274 




3 
R31 I 


33-97 


— ■ ' 


— 


z 


59-40 


Ditto 







3 


33-44 


— 


— ■ 


— 


59-40 


Ditto 


• 




5960 2 


52-0 


— 


- I 


— 


59-40 


Ditto 















Table XIV.— CowpamoM of 




Static 








Impact by 




Ultimate 


Elongation 


Con- 




Work of 






Strength 
Tons 










rupture 




Mark 


Gene- 




Total 


tion of 


Fracture 


K.G.M. 






in.!* 


ral 


Local 


on 2" 

% 


Area 




cb. cm. 








% 


Inch 


% 




















20% cryst. 






3184 B2 


43-97 


15 


•15 


22-5 


31 


80% V.F.C. 


13-85 




3184 B9 


43-43 


18 


-09 


22-5 


31 


V.F. cryst. 


13-65 




3184 B15 


42-89 


15 


•15 


22-5 


31 




13-50 




3184 B26 


42-36 


16 


•18 


25 


36 




14-82 




3198 Bl 


43-26 


12 


•24 


24 


36 




14-51 




3198 B9 


43-80 


15 


■17 


23-5 


36 




14-40 




3198 B17 


43 71 


14 


-17 


225 


39 




13-80 




3198 B24 


42-82 


13 


-18 


22 


36 


5% cryst. 


1319 




2300 Bl 


45-57 


13 


-17 


21-5 


34 


95% V.F.C. 

70% cryst. 


13-70 




2300 B7 


44-24 


13 


■12 


19 


28 


30 V.F.C. 
20% cryst. 


11-75 




2300 B14 


4C-47 


12 


•13 


18-5 


28 


80% V.F.C. 

10% cryst. 


11-76 




2300 B21 


46-05 


15 


•11 


20-5 


31 


90% V.F.C. 
50% cryst. 


13-37 




1324 Al 


46-20 


13 


-09 


17-5 


24 


50% V.F.C. 
70% cryst. 


11-3? 




1324 A7 


46-30 


14 


-08 


18 


22 


30% V.F.C. 
50% cryst. 


11-69 




1324 A14 


44-58 


15 


•10 


20 


28 


50% V.F.C. 
70% cryst. 


12-48 




1324 A20 


45-48 


14 


•09 


18-5 


24 


30% V.F.C. 


11-75 





ON IMPACT TESTS. 



37 



Static and Impud Tension. 
Charpy Apparatus 



Impact. 





Energy of rupture 


] 


Elongation 




Contrac- 
tion of 


Fracture 










^ 






K.G.M. 


KXt.M. 
cb. cm. 


General 


Local 


Total on 
2" 

% 


Area 










% 


Inch 


% 






2S-13 


14-36 


11 


•13 


17-5 


.58-5 


Minutely tino crystalline. 
Silky at edges. 




24-12 


12-06 


9 


-14 


16 


58 


Cup-shax>ed. 




27-30 


13-65 


13 


-12 


19 


59 


Ditto 




31 31 


15-65 


14 


-14 


21 


62-5 


Ditto 




27-86 


13-93 


3 


-18 


15 


.58 1 


Ditto 




32 43 


16-21 






_ 





Ditto 




2616 


13-08 


5 


-11 


15-5 


591 


Ditto 




26-76 


13-38 


9 


•18 


18 


57-7 


Ditto 




28-72 


14-30 


10 


•15 


17-5 


58-4 


Ditto 




30-78 


15-39 


13 


•12 


19 


58-4 


Ditto 







— . 


— 




— 


— 


— ■ 







— . 


; — 


— 


— 


— 


— 






— ■ 


1 — 


— 




" 


~ 



Static and Impact Tension. 
Oharpy Apparatus. 



Impact. 



Energy of rupture 





K.G.M. 


K.G.M. 


cb. era. 


3573 


17-86 


43-02 


21-51 


45-98 


22-99 


42-94 


21-47 


2812 


14-06 


4506 


22 53 


35-83 


17-91 


39-85 


19-92 


32 


160 


3711 


18-55 


39-18 


19-59 


30-0 


15-0 


3916 


19-57 


38-21 


1910 


32-92 


16-46 


43-49 


21^74 



Elongation 



General 



Local 



% 

17 
19 
23 
23 
15 
23 
16 
20 

15 

16 

15 

14 

18 

20 

14 

22 



Inch 

-11 
-12 
-12 
•12 
•05 
•12 
•14 
•10 

-09 

-13 

-13 

-09 

-12 

-10 

-14 

-08 



Total on 

q" 



% 

22 5 

25 

29 

29 

17-5 

29 

23 

25 

19-5 

22-5 

21 5 

18-5 

24 

25 

21 

26 



Contrac- 
tion of 
Area 



38 

41-5 

42 

48-5 

41 

43 5 

41-5 

41-5 

33 

37 

41 

40-5 

42 

40-5 

38 

44 



Fracture 



V.F.C. traces cryst. 
Very fine cryst. 



V'.F.C. traces crvst. 



Very fine cryst. 



38 



REPORTS ON THE STATE OP SCIENCE. — 1018. 



Table XV. — Impact Tension. 

Martens' Drop Hammer. 

Test-piece 10 mm. dia. Area 78'54 sq. mm. 
Weight of tup 36 kg. Height of fall 2 mts. 



No. of Blow. 


Elongation in cm. 


R31 6 5960 5 


Rll 1 R19 1 


on 4'2o" 


on 2-5'' 


1 
2 
3 

4 (necked) 
5 


1-2 -60 

•8 6 
1 -0 broke at 
change of 
section 
•9 — 
broke — 


■38 ' -36 

33 33 

broke broke 




on 4-25" 


on 100 mm. 


Total elongation 
Per cent, elongation 
Local elongation 
General elongation 
Contraction of area 


3-9 1 1-2 cm. 

32% 10% 

60% , 60% 


1-17 1-70 cm. 
11-7 i 17% 
•66 -68 cm. 

5% 10% 
60% 60% 



Table XVI. — Impact Tension. 
Martens' Drop Hammer. 
Test-piece 10 mm. dia. Area 78"54: sq. mm. 



AVeight of 


tup 18 kg. He 


ight of fall 3 mts. 




No. of Blow 






Elongation in em. 




Rll 3 


R19 3 


R31 2 


R31 5 


5960 3 


Gun 
Steel 7 


Gun 
Steel 8 


on 


2" 


on 425' 


on 100 mn 


1. 


1 


■19 


•15 


•20 


•40 


•20 


•28 


•23 cm. 


2 


13 


•13 


•80 


•50 


•60 


•18 


•20 


3 


■14 


■13 


•40 


•50 


•20 


•23 


•18 


4 


•18 


•10 


•50 


•40 


•30 


•20 


•18 


5 


■13 


•08 


■40 


•50 


broke 


•20 


•18 


6 


■15 


•05 


•30 


•20 


— 


•20 


•18 


7 


■18 


broke 


•40 


•40 


— 


•23 


•30 


8 


■30 


— 


•40 


•40 


— - 


•25 


broke 


9 


broke 


— ■ 


•50 


broke 


— 


broke 


— 


10 


— 


— 


broke 


— 


— — 


— 


Total elong. 


onl0( 


) mm. 


on 4-25* 


j on 10 


O^mm. 


213 


1-65 cm. 


3-9 


3 3 


13 cm.! 1875 


145 cm. 


% elong. 


21-3% 


165% 


36-0% 


310% 


12-0% 


18^75% 


145% 


Local elong. 




•68 cm. 


— 


— 


— 


•73 


•56 cm. 


General ,, 


130% 


9-5% 


— 


— 


— 


11-5% 


90% 


Contr. of area 


660% 


60^0% 


58^0% 


57 •0% 


600% 


698% 


631% 



ON IMPACT TESTS, 



39 



Table XVII. — Impact Tension. 

Martens' Drop Hammer. 

Test-piece 10 mm. dia. Area 78-54 sq. mm. 
Weight of tup 18 kg. Height of fall 2 mts. 



No. of Blow 






Elongation in cm. 






Rll 2 


R19 2 


R31 4 


5960 4 


Gun 

Steel 5 


Gun 

Steel 


or 


I 2" 


on 4 25" 


on IC 


K) mm. 
•18 


1 


•13 


•13 


•30 


•20 


•18 


2 


•08 


•06 


•40 


•20 




15 




13 


3 


•08 


•11 


•30 


•20 




13 




10 


4 


•06 


•02 


•30 


•10 




13 




10 


6 


•10 


•10 


•40 


•20 




13 




10 


6 


•06 


•08 


•30 


•10 




13 




10 


7 


•06 


.09 


•20 


•10 




13 




10 


8 


•06 


•11 


•20 


•20 




13 




10 


9 


•10 


•12 


•30 


•20 




13 




10 


10 


•05 


•15 


•30 


•10 




13 




10 


11 


•10 


broke 


broke 


broke 




18 




10 


12 


•10 


— 


— 


— 


broke 




10 


13 


•10 


. — 


. — . 


— 







13 


14 


•14 


— 


— 


— 







18 


15 


•18 


— 


— 


__ 





broke 


16 


broke 


— 


— 


— 


— 


— 


Total elong. 


on 1 


00 mm. 


on 425' 


on 10 


mm. 


215 


1-50 cm. 


300 


1-16 cm. 


155 


1 625 cm. 


% elong. 


215% 


15^0% 


27-3% 


106% 


155% 


16-25% 


Local elong. 


•53 


•61 cm. 


— 


— 


•76 


•58 cm. 


General elong. 


16% 


9% 


— 


— 


8% 


105% 


Contr. of area 


63% 


63% 


60% 


60% 


58 5% 


600% 



40 



REPORTS ON THE STATE OF SCIENCE. — 1918. 





Test on 


Munition and Alloy Steels 


in Static Tension. 








Original 


Stress iu lbs. 


S c 


sticity 
irrors 


■*3 








Dimensions 




e • 


it of Ela 
from 
rtens' m 


Hig 




Test 
Number 


Young's Modulus 






.5 c 

Is. 


.2 o 








1 










Diam. 


Area 


Total ■ 


Per 
sq. in. 


«= 




« 




1 




Inch 


sq. in. 














1324 




















A 20 


2912x10' lbs. per 
sq. in. 


-3949 


•1224 


12,840 


104,900 


46-84 


18-3 


■39 




2300 




















B7 


29-32x10' lbs. per 


•3938 


•1218 


12,030 


98,700 


44 06 


16-5 


-37 




1 


sq. in. 


















3198 




















B 24 


29-04xlOUbs. per 
sq. in. 


•3935 


•1216 


11,800 


97,000 


43 30 


14-7 


34 




3184 




















B26 


28-85x10" lbs. per 
sq. in. 


•3935 


•1216 


11,340 


93,300 


41-70 


14-7 


•35 




Gun 




















Steel 9 


28-80xl0Mbs. per 
sq. in. 


•3932 


•1214 


13,880 


114,400 


51-06 


31-65 

(from 

dia- 


•62 


j 


Gun 


Marten.s' mirrors 












gram) 




1 


steel 10 


not used 


•3940 


•1219 


13,340 


109,500 


48-88 


381 


•78 


i 



-^ 











Tests ( 


m Alloy Steels 


in Te) 


ision. 




Test 
Number 


Young's Modulus 


Original 
Dimensions 


stress iu lbs. 


DO 

I.S 

.S ri- 
al " 

m u 

IS. 

m 


^ Apparent Limit of 
1 9 Elasticity from 
^ Auto-diagrams 


wig 




Diam. 


Area 


Total 


Per 

sq. m. 




Rll 1 
Rll 2 


28^22 xlO« lbs. per 


Inch 

•386 

•3937 


sq. iu. 
•1170 
•1217 


14,110 
14,160 


120,590 
116,320 


5383 
5193 


•93 




R19 1 
R19 2 


sq. m. 
2822 xlO« lbs. per 


•3937 
•3937 


■1217 
•1217 


13,780 
13,640 


113,230 
112,100 


50-55 
5004 


42-6 


•84 




R31 1 


sq. in. 
29-50xlOMbs. per 


•393"? 


•1217 


8,900 


73,150 


32-70 


22-2 


•68 




R31 3 


sq. m. 
29-30xlOMbs.per 


•3937 


•1217 


8,760 


72,000 


32-20 


211 


•66 




5960 2 


sq. in. 
29.00x10' lbs. per 


•3937 


•1217 


13,650 


112,300 


50-15 1 39-0 


•79 






sq. m. 












1 

! 
1 





ON IMPACT TESTS. 



il 



For I 


n^act Repoit 


















1 






fl 


S 


a £ 






Contracted 
Dimensions 


nof Ar 

ent. 


Elongations 

measured 
after fracture 


O 

1 

60 

a 


•.3 
II 


.2 ° 

r, O 


t-5 

•3^ 


Remarks 




.2 " 
g a, 
"S 

6 






s 


IS. 

a 

o 


Total El 
per cent. 


.2 




Diam. 


Area 


on 
i ins. 

Inch 


on 

2 ins. 


Fracture 


Inch 


sq. in. 




Inch 


Inch 


























85% crystalline. 


■35 


•096 


213 


•62 


•37 


•12 


12-5 


lo^o 


19-2 


15% very fine 

ciyst. 
50%" crystalline. 


•34 


•091 


348 


•60 


•37 


•14 


11-5 


150 


16-5 


50% very fine 

cryst. 
20% crystalline. 


■33 


■086 


293 


•68 


•44 


•20 


120 


170 


16-5 


80% very tine 
cryst. 


■32 


•080 


34-2 


■73 


•46 


•19 


13-5 


18-25 


184 


Very fine cry.s- 
tallinc. 


•24 


•045 


62-6 


•51 


•36 


•21 


7-5 


1275 


38 20 


Minutely fine 
cryst., cup- 
shaped. 


25 


■049 


60 


•60 


•44 


•28 


8^0 


15-0 




>> jj 



For Impact Report. 



Contracted 
Dimensions 


1 
11 

o u 

■•ss 

fl 
o 
O 


Elongations 

measured 
after fracture 


§ 

to 
n 
o 

s 

§ 


1 

•gs, 

<B 


a 2 

O 9 


Remarks 


Diam. 


Area 


on 
4 ins. 


on 
2 ins. 


Type of Steel 


Inch 
■236 


sq. in. 
•0437 


02-6 


Inch 
■37 


Inch 
•29 


Inch 
•21 


40 


9 25 


Ni. cr. steel. 


•245 


•0471 


61-30 


•47 


•36 


•25 


5-5 


1175 


Ni. steel. 


•246 


•0475 


59-40 


— 


— 


— 


— 


— 


C. steel. 


•246 


•0475 


59 4 


— 


— 


— 


— 


— 


?S 


246 


■0475 


59-4 


— 




— 


— • 


— 


V. cr. steel. 



42 REPORTS ON THE STATE OF SCIENCE. — 1918. 

ArcJiCBological Investigations in Malta.^Report of the Com- 
mittee, consisting of Professor J. L. Myres {Chairman), Dr. 
T. AsHBY {Secretary), Mr. H. Balfour, Dr. A. C. Haddon, 
and Dr. E. E. Marett. 

Excavations in the Ghar Balam Cave, Malta, in July and August 1917. 

The excavations of the present year were conducted once more 
under the supervision of Mr. G. Despott, Curator of the Natural 
History Museum at the University of Malta. 

Two trenches were dug, one at 50 feet, the other at 110 feet from 
the mouth of the cave ; each of them was about 26 feet long, 4 to 5 feet 
wide, and 12 feet deep — the latter being a depth not hitherto reached. 
A large amount of material, some 70 boxes (five cartloads) in all, has 
to be gone through systematically; the results cannot therefore be 
immediately available. 

Mr. Despott calls particular attention to the discovery of some very 
fine pottery, several implements, a fairly good quantity of human 
remains (no doubt in the upper strata), and the remains of three species 
of elephants — Elephas mnaidrensis, Elephas melitensis, and Elephas 
falconeri (the last two being found in much lower strata than the fir&t). 
The results are described as most satisfactory, and a great deal more 
important than those of last year. 



Exploration of the Paleolithic Site known as La Cotte de 
St. Brelade, Jersey. — Report of the Committee, consisting of 
Dr. E. E. Marett {Chairman), Mr. G. F. B. de Gruchy 
{Secretary), Dr. C. Andrews, Professor Ar Keith, Mr. H. 
Balfour, and Colonel E. Gardner Warton. 

Thanks to a generous grant by the Soci6t6 Jersiaise, in augmentation 
of the sum available from the funds of the British Association, work 
will be carried on during the summer as circumstances permit. Several 
workers have promised to come over from Oxford if allowed to travel. 
Labour will prdbably be available as soon as the potato crop has been 
gathered. 

Excavation is possible in three directions : — (1) The rearward portion 
of the cave-filling needs to be removed, so as to open up the narrow 
outlet to the north at floor level. The amount of rock-rubbish to be 
attacked is not great, but some very large and awkwardly placed blocks 
will have to be broken up. (2) As soon as the floor has been com- 
pletely cleared of the dump in process of demolition, a shaft can be 
sunk near the entrance, so as to explore the lower depths in which 
organic remains are known to occur. (3) A continuation of the rodent 
bed has recently been discovered in the opposite comer of the ravine 
near the spot vi^here Mousterian implements have been found. Unfor- 
tunately the talus is very loose and dangerous here, but means may be 
found to cope with the difficulties. 



ox THE ' FREE-PLACE SYSTEiM. 43 



The 'Free-Place' System. — Report of the Committee, consisting 
of Mr. C. A. BucKMASTER {Chairman), Mi*. Douglas 
Berridge (Secretary), Mr. C. H. Bothamley, Dr. Lilian 
J. Clarke, Professor Barbara Foxley, Dr. W. Garnett, 
Sir E. A. Gregory, Professor H. Bompas Smith, Dr. H. 
Lloyd Snap's, and Miss C. M. Water.s, appointed to inquire 
into and report upon the Effects of the ' Free-Place ' System 
upon Secondary Education. 

I. Introduction. 

The Free-place system is a name given to an arrangement by which, 
in return for certain State grants administered by the Board of Educa- 
tion, secondaiy schools, working in connection with the Board, offer 
a certain number of places in the school, free of all tuition fees, to 
pupils who have had at least two years' previous education in public 
elementary schools. 

At the present time a school complying with the Board's regulations 
as to the provision of free places receives approximately 21. 10s. more 
for each scholar over 11 years of age than a non-complying school. 
This latter class of school i-epi'esents a surviving ' vested interest, ' 
and no additions are made to grants on behalf of those already in it. 

The Boai'd retain power to modify, waive, and interpret their 
i-egulations dealing with these schools and free places and do so with 
a fair amount of freedom. 

Thus certain secondary schools, in receipt of grants from the 
Board, are not required to provide the full 25 per cent, of free places, 
and some schools which before the introduction of the system were in 
receipt of grants are entirely exempted from this condition, receiving 
lei5s gi'ant in consequence. 

The ostensible object of this grant was to offer facilities for secon- 
daiy education to boys and girls whose parents could not afford to pay 
secondary school fees. It was to assist the poor to secure higher 
education for then' children. But the detennination of the question 
as to who should and who should not be thus helped on the ground of 
poverty was obviously beset with the most serious difl&culties, and the 
Gordian knot was cut by assuming that all parents who sent their 
children to the public elementary schools of the country might legiti- 
mately be considered to be in need of assistance in meeting the expense 
of secxsndaiy education for their ohildi'en. A precedent for this 
conclusion already existed ; for many years previously the Science and 
Art Department, with the sanction of the Treasury, had extended to 
all children attending elementaiy schools the classification of ' indus- 
trial, ' and had interpreted ' industrial ' as equivalent to an income not 
exceeding 150L a year. The two tests are not, however, identical. 



44 REPORTS ON THE STATE OP SCIENCE. — 1918. 

Just as in practice the requirement of the State that all children 
must be educated means that only persons living in houses below a 
certain rateable value are ever called upon by the educational authority 
to send their childi-en to an efficient school, so the mere fact of attending 
a public elementary school is in its turn taken as evidence of straitened 
means. As a compromise it is perhaps satisfactory : as a real solution 
of the difficulty it seems illogical and haphazard. 

The condition that a certain proportion of free places was to be 
reserved for pupils from public elementary schools came into force 
in 1907 when Mr. Reginald McKenna was President of the Board of 
Education. In the estimates for that year an additional sum of 
75,000Z. was taken for secondai-y schools and an additional 120,000^ 
in the following year. Mr. McKenna, in explaining these estimates 
to the House of Commons, said: ' These free places must not be con- 
fused with scholarships. They would be for public elementary school 
children who would not be asked to compete with children outside. 
They would only be asked to pass a qualifying examination. The 
general rule wovild be that any school receiving the additional grant 
(provided for in these estimates) should offer at least 25 per cent, of 
its places for public elementary school children who should enter free. 
There were cases where, however, 25 per cent, of the places would not 
be used in any case in this way, and in these cases it is proposed to 

give the Board of Education power to waive the requirement 

The increase in grant was in the ratio of 3 to 5. . . . The policy of the 
Board was to democratise the secondai-y schools by raising the general 
level of education and securing for the humblest in the land the oppor- 
tunity of education for their children in really good schools. ' 

Objection was raised during the debate that even 25 per cent, of 
free places was not enough and that all restriction on the number of 
such places should be removed. To this objection Mr. McKenna 
replied that ' while a school might be with or without fees, whatever 
the scale of fees was it must be approved by the Board of Education. 
The schools might have as many more free places (than 25 per cent.) 
as they liked, and he personally trusted that where the school was 
provided by the local education authority the places would all be free. ' 
(Times Report.) 

He further pointed out that his proposals would divide secondary 
schools into two groups, viz. : those that elected to go on as before 
v/ith the previous scale of grants and those that decided to comply 
with the 26 per cent, rule and receive grants on the new and higher 
scale. 

In the course of this debate Mr. McKenna also stated that at that 
time there were 600 secondary schools recognised by the Board of 
Education, and that these schools had a total of 104,938 scholars of 
whom over 56,000 came from public elementary schools, and of these 
29,000 paid no fees at all. 

In the previous year a departmental committee of the Board of 
Education had reported on the question of admission to secondary 
schools of children unable to pay the full school fee, and this report, 



ON THE ' FREE -PLACE ' SYSTEM, 45 

which has not been made public, may be assumed as the basis on which 
'Mr. McKenna's system was built. 

In the report of the Board of Education for the year 1906-7 
reference is made to the free-place question as follows: — ' The oppor- 
tunity which an increase of grant has offered has been used to secure 
that all secondary schools aided by grants shall te accessible to alf 
scholars who are quahfied to profit by the instruction given therein. 
The fees charged . . . have in many cases constituted a barrier to the 
admission of children of working men who are desirous to obtain and 
able to profit by secondaiy education. ... It is not unreasonable to 
require that, in retura for additional financial aid, the authorities 
responsible for the schools should admit fi'ee a certain number of 
children from public elementary schools. It is accordingly laid down 
that in all schools where a fee is charged a proportion of places, which 
will ordinarily be not less than one quarter, shall be open without pay- 
ment of fee to scholars from public elementaiy schools applying for 
admission provided that the apphcants are able to show by a qualifying 
examination their fitness to profit by the education given in the school.' 
(Times Summai-y, December 31, 1907.) 

It is of interest to note that in the Training College regulations 
for the same year emphasis is laid on the condition that students 
may only be excluded on ' reasonable grounds, ' and that exclusion on 
the grounds of religion or of social status is not 'reasonable,' thus 
corresponding to the policy of the Board in regard to admission to 
secondary schools in relation to social position. 

It would appear that in actual practice a school can comply with 
this 25 per cent, rule if one quarter of its scholars come from pubhc 
elementa,ry schools and are not paying fees either as holders of school 
scholarships, county scholarsliips, local or other scholarships, or for 
other reasons. As such scholarships are generally awarded by a more 
or less rigid competitive examination, it is theoretically possible that 
a school might still comply with the 25 per cent, free-place rule and yet 
not have offered any fi'ee places not attached to specific scholarships. 
Tliis is, however, not a very likely result, and the general position is 
fairly summed up in the words of a recent report to the Kent Educa- 
tion Committee while referring to the free-place system : — 

' No special preparation is necessaiy for free-place scholars at 
secondary schools. The school record and the oral test ai'e of decisive 
importance and any written examination is only preliminary. The 
object of the examination is to select, not so much the children who 
are superior to their fellows in present attainment, as those who give 
evidence of superior aptitude and intelligence, and in making the award 
adequate attention is given to character and physical health.' 

This may, we think, l)e taken as an admirable exposition of the 
award of free places at its best. 

The free-place system is in fact a compromise, and grew oiii of a 
struggle, none the less real because veiled, between the more radical 

1918. B 



46 REPORTS ON THE STATE OF SCIENCE. — 1918. 

local authorities of the North of England and the Board of Education as 
successor to the defunct Science and Art Department. 

Under the latter body School Boards had established science 
schools supported partly by grants for science, art, and manual instruc- 
tion, and attended by children of both sexes who had passed through 
the ordinai'y elementary school curriculum and wanted some further 
education. When, as a condition of the grants, these schools were 
urged to provide efficient literary instruction in English and at least 
one modern language they became secondary schools in all but name, 
and flourished for a time exceedingly. But the decision in the 
Brighton case, followed by the famous Cockerton judgment, that a 
School Board could not legally spend the rates on schools of this type, 
%\ hich were, as a rule, without fee or with fees not exceeding a shilling 
s week, led ultimately to the abolition of the School Board system and 
the creation of the local education authorities, with definite powers 
for secondary education, in its place. Several of these new local 
authorities followed the policy of their School Board predecessors and 
kept the fees of the reconstincted organised science schools at an 
almost nominal sum since the Board of Education's regulations 
required a fee of some amount to be charged. 

The Board stroA^e for some years to raise the school fee — not, it 
must be admitted, from a desire to exclude the poorer children from the 
schools, but from a wish to increase the school's resources, to emphasise 
the importance of secondary education, and to squeeze out all childi'en 
who were not determined to take their secondary school training 
seriously and stay at school sufficiently long to profit by the school 
instruction. The opposition, represented by certain local authorities, 
concentrated its efforts in making secondary education as accessible as 
possible to any child that desired it, and as a result of these contrary 
forces in truly English fashion the free-place expedient was devised. 
Like many other illogical devices it has shown during its ten yeai's' 
existence that it is workable and that it possesses a remarkable amount 
of vitality. Whether in the immediate future it will be superseded by 
some more comprehensive system it is impossible to foresee. 

II. Summary of Information derived from the Heads op Schools. 

Copies of a questionnaire were sent to the 910 schools which receive 
grants from the Board of Education; 384 replies (4'2 per cent.) have 
been received. 

A very large number of schools say they are quite satisfied with the 
present working of the system ; others, whilst not objecting to the 
principle of the system, point out difficulties they have found in its 
working, or make suggestions for improving it. In this analysis more 
attention is natui'ally given to suggested alterations than to expressions 
of perfect agi'eement ; but it must be remembered that as far as the 
evidence goes the system is working very well in the large majority of 
those schools whose pupils are drawn from the elementary schools to 
the extent of more than 50 per cent., including free-place holders. 



ON THE ' FREE-PLACE ' SYSTEM. 47 

Mode of Admifssion. 

In the majority of cases this is by means of a written competitive 
examination, but a considerable number of schools add an oral test 
which is often conducted by the head of the secondary school and 
sometimes in presence of a representative of the elementary schools 
and (oi') an education officer. When this oral test is made, the object 
is generally to determine the general intelligence of the child as con- 
trasted with its mere knowledge (see under ' Ability '), but sometimes 
it is used as a means of finding out whether the parent on the one hand 
can afford the necessary books, &c. (see mider ' Finance'), oi*, on the 
other, if he requires the financial help of a free place, and also whether 
the parent will keep the child at school for a sufficient time to enable it 
to benefit by beginning a secondary education. In a few cases the 
parent is obliged to sign an undertaking to keep the pupil at school 
until he or she has reached the age of 16. (See under ' Finance. ') 

In cases Where the admission is by means of a competitive examina- 
tion, the actual competition is of the most varied kind ; in large schools 
of high reputation situated in important towns, there are often ten 
candidates for each vacant place; in the country schools, however, 
complaint is frequently made that ' there is no real competition ' ; 
' less than half marks qualify ' ; ' almost anyone can gain a free place. ' 
In considering the replies as to the ability of the pupils it is necessary 
to bear these facts in mind. 

Proportion reaching Matriculation. 

A very large number of schools have made returns purporting to be 
the percentage of free-placers who reach matriculation standard; since, 
however, these returns are very difficult to understand they are not 
included in the present analysis — e.g., a large school in the Midlands, 
which is represented, on the Headmasters' Conference and has obtained 
a large number of University scholarships, states that 13 per cent, of 
the free-placers reach matriculation standard, whilst a small mixed 
school in the North of England gives the percentage as 80 ; this is only 
one of the many examples, and it would seem that either educational 
results vary inversely as the standing of the school, or that different 
headmasters have different ideas as to what is meant by ' matriculation 
standard.' It is probable that the explanation is to be found in the 
following, which is typical of a large number received: — ' A satisfactoiy 
proportion reach the standard of the Junior Oxford and Cambridge Local 
Examinations; a few reach matriculation standard, but the majority 
leave at too early an age to do so. ' 

Speaking generally, it seems that those free-placers who are capable 
of benefiting by a secondary education at all, reach the average standard 
of the school ; whilst in schools where the large majority of the pupils 
have been in elementary schools the standard reached by free-place 
holders may be higher than that reached by others. 

Physique. 

Only two schools report thet the physique of the boys is insufficient 

e2 



48 REPORTS ON THE STATE OP SCIENCE. — 1918. 

to stand the strain of a secondary education; in the case of girls, how- 
ever, it is sometimes mentioned that home duties after school hours, or 
long journeys home (either by train or bicycle), impose a strain which 
prevents them from obtaining the full advantage of a secondary school 
life. 

Games and Corporate Life. 

In schools with a large proportion of ex-elementary pupils there is, 
of course, no difficulty ; some of the other schools report that the free- 
placers keep themselves too much to themselves — it is never mentioned 
that the fee-paying pupils keep themlselves apart irom the others, but 
this possibility must not be lost sight of. Speaking generally, free- 
placers seem to join in the giames and corporate life of the school as far 
as their journey home and financial considerations allow. — (See under 
' Finance. ') 

Ability. 

Opinions as to the ability of free-placers vary much; in schools 
where the percentage of ex-elementary pupils is high they are generally 
said to be above the average. In schools with a smaller percentage 
of ex-elementary pupils the opinion is less complimentary, and the 
following complaints have been received: — 

(1) The average ability is satisfactory, but they reach the limit of 
their capacity for advanced work sooner than do the others. 

(2) A considerable number are quite unfit to benefit from a 
secondary education. 

(3) Tlie competitive examination that is held fails to discover the 
best candidates ; this is partly due to the essential difference between the 
curricula of the elementai-y and secondary schools; the mere fact 
that the children can write neatly and sum coiTectly is no proof that 
they can benefit from the study of languages and mathematics. 

Industry. 

A vei'y few complaints have been received under this head ; and those 
few will be considered under the paragraph ' Tenure and Finance. ' 

Character. 

A number of complaints have been received respecting the moral 
attitude of free-place holders, especially in regard to their ideas of 
school honour. Some schools report a considerable improvement in this 
respect during their secondary education. Other and less frequent 
complaints are: — 

(1) liSick oi esprit de corps ; (4) Bad manners; 

(2) Want of ambition ; (5) Lack of modesty (from a girls' 

(3) Want of personal cleanliness. school). 

It is probable, however, that hardly any of these complaints can be 
urged against the free-place holders per se. 

Curricnluvi. 

The incorporation of free-place holders with the class organisation 
of schools is often attended with difficulty, especially in schools where 



ON THE ' FREE-PLACE ' SYSTEM. 49 

the percentage of ex-elementaiy pupils is small ; the difficulty mentioned 
is that the childi-en have not begun Latin, French, science, or mathe- 
matics; it is also added by a few schools that the high standard 
obtained by the free-placers in arithmetic causes trouble. 

Although many schools mention the difficulty, it does not seem to 
be acute if the free-placer enters at or under the age of 12 ; for in this 
case an extra lesson in the afternoon during one term, or an arrange- 
ment for teaching the lower fonns in sets, enables the more able pupils 
to catch up the others. In the case of those who enter above the age of 
13 it is, however, frequently mentioned that the whole curriculum of 
the school is upset, the fee-payers are retarded in their progress and 
the free pupils fail to benefit from their lessons ; it is generally agi-eed 
that no free piece should be given to such children, and, since no school 
is required by the Board of Education to admit free-placers over 13 
years of age, the difficulty, such as it is, must be considered to be 
created by the schools or the authorities themselves. 

Dinners. 

Although one lai'ge school wrote asking how it was possible for there 
to be any difficulty in the matter of school dinners, a very considerable 
number state that they are a constant problem. The schools situated 
in large towns and drawing then- pupils from their own immediate 
district seldom make provision for dinner, but in those attended by 
pupils from a distance it is very common for a meal to be provided at 
a cost of from id. to 9d. per day ; the usual charge is 6(/., but one school 
states that they provide a non-meat meal at 3d. ; in very many cases the 
free-placers cannot afford even this, and .tlie resulting problem is met in 
various ways. The London County Council, the Kent Educational 
Authorities, and possibly some others seem to make special main- 
tenance grants to cover the cost. In some cases where pupils, whether 
free-placers or others, bring sandwiches a separate room or a separate 
table is provided; one girls' school mentions that every effort is made 
to make this table as attractive es possible by placing flowers, &c., upon 
it. At one large school for boys some of the free-placers earn their 
dinners by waiting upon the others first and taking their own when the 
oixlinary meal is over. In many cases, however, the matter seems to 
be left to private charity, often that of the head of the school or 
Governors. 

Amongst the schools wliich find a difficulty in the matter of dinners, 
there is a general agi^eement that the children require a good meal in the 
middle of the day. 

Social Status. 

Several schools state that since they received free-placers the 
' better-class ' parents have withdrawn their children and it has been 
necessary to reduce the boarding fees ; a few state that this may be 
' snobbishness, ' but it is a fact they must take into consideration. It 
seems, however, certain that this class exclusiveness is becoming less 
strongly marked, and need not be considered a serious obstacle to the 
development of the system. 



50 REPORTS ON THE STATE OF SCIENCE. — 1918. 

Tenure of Free-Placers and Financial Considerations. 

These two subjects are so frequently reported upon in the same 
connection that it is convenient to consider them together here. The 
chief complaints are: — 

(1) Free-placers are under no obligation to give notice, they can 
' just stay away ' at will; a fee-paying parent can be sued for a term's 
fees if a pupil is withdrawn without notice, but this is not possible in 
the case of a free-placer, unless a definite undertaking has been given by 
the parent. 

(2) Free-placers are very frequently withdrawn from schools after 
about two years — i.e. before they have been really able to benefit from 
a secondary education; this is sometimes caused by the parents being 
unable to keep their children at school longer without a maintenance 
grant ; sometimes because the child is only ' sent to a secondary school 
in order to obtain testimonials ' ; and sometimes because the child does 
not wish ' to be bothered ' by having to prepare for examinations. 

(3) Some schools report that they only accept free-placers whose 
parents sign an undertaking to keep them at school until the end of 
the school year in which they become 16 ; and cases are on record 
where damages have been recovered when such an undertaking has 
been broken. 

(4) The very poor can seldom, if ever, allow their children to accept 
free places without some form of maintenance grant. 

(5) In many schools where there is a games subscription some of 
the free-placers can only pay this if there is a maintenance grant ; failing 
this, they are cut off from much of the corporate life of the school. 

(6) It is impossible for children to travel long distances to school 
and to stand the mental and physical strain of life in the secondary 
school unless they have a good meal in the middle of the day; many 
of the free-placers cannot afford this without a maintenance grant, and 
they consequently fail to derive much benefit from their post-elementary 
education. 

(7) Many free places are given to children whose parents can well 
afford to pay the fees : it is reported by many schools that most of their 
fee-paying pupils are those who have tried for but failed to obtain a 
free place ; others report that quite well-to-do people send their children 
to elementary schools and then pay for extra coaching to enable them 
to gain free places; wliile one boarding school was asked to receive as 
a boarder a child who was in the school as a free-placer. 

In connection with this point, one school suggests that it is unfair 
to prevent those parents who have made an effort to send their children 
to secondary schools from receiving the benefit of a free place, the more 
so since such children would as a rule afford better material to build 
upon. 

(8) The rule that no one can be deprived of a fi'ee place for an 
offence which would not cause the expulsion of a fee-payer has the effect 
of keeping in school pupils who, because of unsatisfactory character or 
lack of industry or ability, ought not to be educated directly or indirectly 
at public expense. 



ON THE ' FREE-PLACE ' SYSTEM. 51 

The following are the chief alterations suggested by the teachers : 

(1) Free places sliould at first be awarded for one year only, with 
power of renewal. 

(2) Power should be given to the Governors to withdraw free 
places from those whose reports are frequently bad. 

(3) Free places should only bo given to those in need of financial 
assistance. 

(4) The money now wasted upon pupils who are unlikely to benefit 
from a secondary education should be devoted to providing maintenance 
grants to the more deserving. 

(5) When school dinners are pi'ovided, the free place should be 
combined with a maintenance gi-ant, paid direct to the school, to cover 
the cost of this. 

(6) Maintenance grants should, when necessary, be made to keep 
former holders of free places at one of the Universities. 

(7) A grant should in all cases Ije made to cover all games subscrip- 
tions and railway tickets to school matches, &c. 

III. Summary of Information derived from tub Officials of 
County and Borough Authorities for Higher Education. 

Requests for an expression of opinion on the free-place system were 
sent out to the 50 Counties and 75 County Boroughs in England that 
are responsible for the local control of higher education. 

Eeplies were received from 36 Counties and 45 County Boroughs — 
i.e. from 65 per cent, of the whole number. Quite a number did more 
than answer the five main questions, and supplied full descriptions of 
their schemes and opinions as to their working. These fuller answers 
were most helpful in arriving at a fair judgment of the trend of adminis- 
trative thought. 

1. The chief fact that emerges clearly from tlie returns is that 
County Scholarship Schemes and Free Places tend to merge into one 
system. It will perhaps be well to put clearly here what is historically 
the difference between the two classes, for in many areas the difference 
is purely historic and no longer exists. Before the rule was established 
that grant-earning schools must normally offer each year free places 
to the number of 25 per cent, of the total entrants to the school of the 
previous year, many local education authorities gave scholarsliips to 
secondary schools to boys and girls at about the age of 12. These 
scholarships sometimes carried more than free education, providing 
travelling expenses, books, and maintenance allowances of vaaying 
amomits. They were usually for a period of thi-ee or four years, rarely 
longer, and only a few holders, with the help of intermediate scholar- 
ships, stayed the full life of a secondary school np to 18 years of age. 
The Board's free-place scheme cut across these arrangements. The dis- 
tribu.tion of free places depended on the situation and numbers of the 
secondary school, not on the juvenile population of the district, and 
the period of tenure was ' up to the school-leaving age. ' Authorities 
therefore had two paths to choose from ; they could either turn their 
county scholars into ' free-placers ' by extending the period of tenure 
up to the age of 18, adding or subtracting where necessary to make 



52 REPORTS ON THE STATE OF SCIENCE. — 1918- 

up the 25 per cent., or they could keep their scheme for county scholars 
intact and add another for free-placers to meet the Board's demands. 
The returns show that, in the area of at least two-thirds of those making 
returns, whether Counties or County Boroughs, the former scheme has 
been adopted. Free-piece holders and county scholars are indistin- 
guishable. Only in a few instances do the returns show whether this 
has meant the combination of the advantages of both schemes. The 
lengthened tenure is obligatory, but it may be balanced by dropping 
the allowance previously given to county scholars for travelling, &c., 
the Board's scheme demanding merely freedom from tuition and 
entrance fees. Some indication of what has happened may be gained 
from the name retained; where all are called county scholarships the 
incidental advantages often remain ; where all are called free places 
they carry as a rule nothing but the minimum requirements of the 
Board. The existence of two 'Schemes side by side is certainly con- 
fusing and must add to the trouble of administration. 

2. Travelling expenses are paid to holders of free places in 26 
Comities out of 36; in the County Boroughs they are apparently 
considered unnecessary. 

Maintenance allowances of some kind are paid in 61 per cent, of 
the areas, but they are very small indeed, usually confined to ' neces- 
sitous ' cases, and sometimes to those over 14 years of age. County 
Councils seem slightly more generous than County Boroughs, but this is 
probably due to the factor of distance, which makes some contribution 
to the cost of dinner at school imperative. Few allowances rise to a 
figure beyond that needed to cover this single expense. In areas where 
there is a double scheme of county scholarships and free places the 
allowances for travelUng and maintenance are frequently confined to 
the former, who represent the pick of the candidates in the examination. 
As the capacity to do well in an examination bears some relation to the 
relative poverty and consequent ill-feeding of the child, this results in 
the poorer children obtaining the least help ; where travelling expenses 
ai'e not covered the free places are not really open to the country 
labourer's child. 

3. The returns as to ability of holders of free places compared with 
other pupils are rather indefinite. Of those who rephed to the question 
about 40 per cent, of the County Boroughs and about 30 per cent, of 
the Counties consider the free-place holder above the ordinary fee- 
paying pupil in ability. 

4. Very few of those who sent returns have any belief in Higher 
Elementary Schools, 8 among the Counties and 5 among the County 
Boroughs alone holding that some of the children might do better there 
than iu secondary schools. There is, however, a considerable body 
of opinion that Junior Technical Schools would be useful in this way. 
This is especially the case among the Counties. 

The chief trouble is the shortness of the school life of the secondary 
scholar, and this makes some of the officials think that three years in a 
technical school would be a better investment. Where a full four or 
five years' course is taken most of the returns are that the results are 
satisfactory. 



ON THE ' FREE-PLACE ' SYSTEM. 53 

5. The tendency of teachers in elementary schools to keep back 
their pupils from competing for scholarships is reported as decreasing 
and now only occasional. In this matter the teachers in the County 
Boroughs seem in advance of those in the Counties, but it must be 
remembered that in country districts the facilities for making use after- 
wai'ds of a secondary education are much less than in the town, and 
teachers may well hesitate to urge any but the cleverest to make the 
necessary sacrifices. These, too, are gi-eater for the country than for 
the town parent from the nature of the case. 

IV. Numerical Analysis of Opinions eecexved from the 
Schools affected. 

Percentage of the schools not satisfied with the system : — 

Schools with more than 40 per cent, of free-place holders . 30 per cent. 
„ „ between 20 s>nd 40 per cent. ,, „ . 45 per cent. 

„ „ less than 20 per cent. ,, „ .54 per cent. 

♦Schools with more than 40 per cent, of ex-elementary pupils 42 per cent. 
„ „ between 20 and 40 per cent. ,, „ 66 per cent. 

„ „ less than 20 per cent. ,, ,, ,, 58 per cent. 

More are satisfied in large towns where competition is keener and 
the standard consequently higher. 

Masters seem more easily satisfied than mistresses — e.g. : 

Satisfied. Not Satisfied. 

Girls 48 60 

Boys 66 51 

-Mixed 40 19 

Complaints about character came from 32 per cent, of Girls' and 11 per cent. Boys'. 
Complaints about late entri- came from 6 per cent, of Girls' and 3 per cent. Boys'. 
Complaints about strain came from 4 per cent, of Girls' and 2 per cent. Boys'. 

On questions re Social Stai.us, Dinner Difficulties, Ability and Cur- 
riculum, the complaints are about equally divided between the Boys' 
and Girls' Schools. 

V. The Percentage of Free-place Children actually in the 

Schools. 

The following numbers are obtained from ' Statistics of Public 
Education,' 1913 and 1914: — 

Fee-paymg Pupils : Boys. Girls. 

Ex-public Elementary Schools . . 33.8 27.2 

Other Schools .31.1 35.3 

64.9 62.5 

Free Pupils : 

Ex-public Elementary Schools . . 33.3 35.4 

Other Schools. ..'.... 1-8 • .1 

35.1 37.5 

* It must be remembered that the number of ex-clementar\- pupils in any school 
is almost always in excess of the number of free-place holders, and that consequently 
these two sets of results are based upon different data. 



54 



REPORTS ON THE STATE OF SCIENCE. — 1918. 



The percentage of free pupils admitted during the year is given : — 



Boys. 

Fee-paying Pupils 70.2 

Free Pupils 29.8 



Girls. 
69.1 
30.9 



These numbers point to the duration of school life being greater 
amongst the free pupils than amongst those who pay fees. 



The Age at which Free Pupils are Admitted. 



' Statistics of Public 


Education ' give 


figures from 


which 


following are calculated : - 


— 












Fee Paying. 




Free 


Pupils. 






Boys. Girls. 




Boys. 


Girls 


Under 9 yeai 


•s of age 


. 8.3 8.9 




fi.O 


0.0 


9 and under 


10 . 


. .5.9 4.3 




.2 


.1 


10 „ „ 


11 . . 


. 7.7 6.3 




2.2 


1.5 


11 „ 


12 . . . 


. 9.9 8.9 




9.4 


8.8 


12 „ „ 


13 . . . 


. 15.3 14.1 




13.0 


12.8 


■•'* Sf J> 


14 . . . 


. 13.5 13.2 




3.9 


4.7 


Over 14 . 


• • • ■ 


. 9.6 12.2 




1.1 


3.0 



the 



70.2 



68.9 



29.8 



30.9 



In order to compare the age at entry of the two classes it is con- 
venient to obtain a percentage of each separate class. "^^ 









Fee Paying. 








Boys. Girls. 


Under 9 






. 11.8 13.0 


9 and under 


10 . . 


.84 6 2 


10 „ 


5» 


11 . 


. 11.0 9.1 


11 „ 




12 . 


. 14.1 13.0 


12 „ 




13 . 


. 21.8 20.5 


13 „ 


>> 


14 . 


. 19.3 19.1 


Over 14 






. 13.6 19.1 



. This 


gives : ■ 


Free 


Pupils. 


Boys. 


Girls 


0.0 


0.0 


.7 


.3 


7.3 


4.9 


31 5 


28.5 


43.6 


41.4 


13.0 


15.2 


3.9 


9.7 



100.0 



100.0 



100.0 



100.0 



CONCLUSIONS AND RECOMMENDATIONS. 

N.B. — Dr. Suape was prevented by impaired health from attending the 
meetings of the Committee and preferred, as he had not had the 
opportunity of participating in the discussions, not to sign this report. 
Mr. Bothamley is not i)i agreement with the terms of Recommenda- 
tion 8, which is therefore put forward in the name of the remaining 
members of the Committee. 

1. The replies received to the questions asked from the various 
authorities prove that the system is, as a whole, acting well in schools 
in which more than 50 per cent, of the pupils are drawn from the 
elementary schools ; the difficulties met are almost entirely confined to 
schools with a smaller percentage of ex-elementary school children. 
There is, however, but little doubt that some of the children now holding 
free places would derive greater educational benefit from a course at 
a higher elementary, junior technical, or trade school. 

2. Free places should not be awarded to children entering the 



ON THE * FREE-PLACE ' SYSTEM. 55 

secondaiy schools over 12 years of age ; otherwise the work of such 
schools suffers. 

3. A good mid-day meal is essential for those who have to attend 
school at some distance from their homes ; but the average charge for 
this is more than the parents of many free-place holders can affoi'd to 
pay. It should be the duty of the school or the local authority to see 
that no scholar's education is impaired from this cause. 

4. To make the free-place system fully efficient it is necessary that 
in many cases maintenance grants should be given for the years of 
school life above the age of compulsory attendance at a full-time day 
school. This grant should) be of about the value of the average wage 
of the children of the same age in the district ; and should be made by 
the local education authoiity, acting on the advice of the school 
authorities ; and this advice should be given only after careful inquiry 
into the needs of each individual case. If such grants are made it is 
believed that the present temptation to parents to remove promising 
pupils from secondaiy schools before they have been able to derive 
full benefit from them will be removed. 

5. The strength and efficiency of the free-place system is dependent 
for its success on the provision of greater facilities for the support of 
secondaiy school children of exceptional ability at the Universities and 
higher technical schools; this can be met only by the provision of 
a larger number of scholarships from secondary schools, and these 
of greater value than is at present the case. 

Unless supplemented by large school scholarships it is, for example, 
nothing but a mockery to offer a scholarship of 40/. or 50L a year tenable 
at Oxford or Cambridge to a candidate whose home circumstances do 
not pennit of a very substantial addition thereto being made. 

6. It should be possible to i-emove from the free-place list the names 
of pupils who ai'e reported for habitual laziness ; such removal to be 
made by the governing body of the school acting upon the report of 
the head-master. 

7. The award oi a free place should not be based exclusively upon 
the results of a written examination, but in conjunction with an oral 
examination conducted by the head of the secondary school with the 
aid of one or more persons appointed by the local education authority 
from the contributory schools. 

8. The free-place system should be available for all classes of the 
community; those parents who have made an effort to forward their 
children's education by paying fees for them whilst young should not 
be prevented, as at present, from gaining the benefit of a free secondary 
education ; the difficulty may probably be best met by i-uling that all 
candidates must have been educated for two years in a school inspected 
by the Board of Education and classed by that Board as ' efficient. ' 



56 REPORTS ON THE STATE OF SCIENCE. — 1918 



Plant Pathologij. — Report of the Committee, consisting of Pro- 
fessor M. C. Potter (Chairman), Dr. E. N. Thomas (Secre- 
tary), Professors B. T. P. Barker,, Biffen, and V. H. 
Blackman, Mr. Brierley, Mr. P. T. Brooks, Mr. 
Cotton, Professor T. Johnson, Drs. F. W. Keeble and 
G. H. Pethybridge, Messrs. J. Eamsbottom and W. Eobin- 
soN, Dr. E, J. EussELL, Mr. E. S. Salmon, Miss A. Lorrain 
Smith, Dr. W. G. Smith, Mr. H. W. T. Wager, and Miss 
E. M. Wakefield, tqjon the necessity for further provision 
for the Organisation of Research in Plant Pathology in the 
British Empire. 

The Cominittee appointed last July have met on several occasions and 
veiy carefully considered the position with regard to the necessity for 
'the provision of further facilities for the organisaition of research in 
plant pathology in the British Empire. 

They confine their remai'ks in the present report to the consideration 
of conditions in Great Britain. 

They conclude that the present opportunities for training, reseai'ch, 
and correlation in plant pathology are quite inadeqixate. 

They are of opinion that there is grave necessity (see Appendix A) 
for the provision of furthei* facilities for the oi'ganisation of research 
in plant pathology, and that the following developments must be 
secured : — 

1. The establisliment of a central institute devoted to the study of 
plant disease, and the establishment of a laboratory for the supply of 
pure cultures.^ 

N.B. — It is realised that it may not be possible, or at any rate con- 
A-en;ien.t, for such an Institute to attempt to cover the whole field of 
agricultural, horticultural, and arboreal plant disease. 

2. The encouragement of local Stations for the study of such aspects 
as local conditions of produce, climate, kc, make particularly possible 
or desirable (as, for instance, in fruit-gi'owing ai-eas, Ac). 

3. The encouragement at the Universities of instruction in the 
phenomena and underlying scientific principles of plant disease. 

A. The insistence, ,as far as possible, upon the study of chemistiy, 
physics, and bacteriology as a necessary preliminary to k'aining in 
plant pathology, which should be approached pi'eferably by way of a 
degree in botany, followed by research work at an institution of experi- 
mental phyto-pathology. 

5. The production of a new publication for the inclusion of abstracts 
and research in plant pathology. 

* The Committee is informed that there is every reason to suppose that a central 
institute is about to be established. 



ON PLANT PATHOLOGY. 



57 



APPENDIX A. 

FRUIT. 
Apple. Losses. 

Scab. Fmidadium dtndritimm General over England, causing falling of young 

fruit and largely responsible for supplies of 
small, iJoor fruit, which does not keep well. 
Could be controlled by spraying. 
Brown Rot. Monilia fntdigena Probably large. 

Blossom Wilt. Monilia cinerea . A serious disease, specially in the S.E. counties. 
Canker. Nectria diiissima . . Severely cripples the trees, especially on wet, heavy 

land, and responsible for heavy losses. 
Mildew. Podosphaera leuco- Seriously injures certain varieties in various 
tricha localities. 

Bitter Pit Fruit badly damaged in some localities. 

Silver Leaf. Stereum purpiireum At present not believed to be serious in apples. 

Peak. 
Scab. Fitsidaditim pirinum . Often very bad, and causing serious losses. 

Could be controlled by spraying. 
Brown Rot. Monilia fnictigena • 

Plum. 
Silver Leaf. Stereum purpureum Very serious in Victoria and Czar plums. 

Threatens their extinction in some localities. 
Causes much loss of young wood and fruit in some 

localities. 
Causes early defoliation in certain seasons. 



Brown Rot. Monilia cinerea 



Rust. Puccinia pruni 

Black Currant. 
Rust. Cronartium ribicola 



. Very bad in many counties in 1917, causing early 

— defoliation. 
Spot. Gloeosporium ribis . 

Gooseberry. 

American Mildew. Sphaero- Formerly very serious in many parts. Much less 

theca mors-tivae in 1917. 

Die-back. Botrytis cinerea . Serious in many localities. 



Wheat. 
Puccinia glumarum 



Ophidbolus 
Puccinia graminis 
Titletia tritici 

Barley. 

Ustilago hordei 

HelmintJwsporium 

Ophidbolus 

Oats. 
Rust. Puccinia spp. 
Ustilago avenae 
Ophiobolus 



CEREALS. 

Sometimes serious. 10 per cent. 

quarters per annum. 
Locally serious. 
Sporadic. 
In aggregate quite material. 

Often serious. 
Often serious. 



800,000 



Often serious. 



Losses. 



Clover. 
Sderotinia trifoliorum 



FODDER. 

Very common locally, and probably largely re- 
sponsible for clover sickness. 



58 REPORTS ON THE STATE OF SCIENCE. — 1918. 

ROOTS. 
Carrot. Losses. 

Sderotinia sderotionun . . At times destructive in store. 

Turnip and Swede. 

Plioma napobrassicne . . . Very destructive locally in the North. 

Bacterial Diseases . . . Very bad at times. 

Finger and Toe .... Widespread, and very destructive in certain 

localities. 
Mangels. 

Rhkoctonia violacea ... At times destructive, 

Phoma betae Locally destructive. 

POTATOES. 
Blight. Phylophthora injestans Average loss in British Isles one ton or more per 

acre. Administrative action taken. (Spray- 
ing.) 
Wart Diseases. Syncliylrium Very serious indeed. Administrative action 

eivdohioticiom taken. (Immune varieties.) 

Black-leg. Bacilhis phytophOior- At times very considerable and apparently 
pus increasing. Inspection of growing seed crop 

necessarj'. 
Corky Scab. Spongosjiora sub- Difficult to control. Locally bad. 

terranea 
Sderotinia sderotioriim . . Bad in West of Ireland. 
Leaf Curl. (Probabli/ physio' Bad, especially in gardens and allotments. 

logical) 
Bacilhis solanaeearum . . . ? Good seed essential. 

Sprain ? 

Dry Rot. Fusarium caenileum . Causes serious losses in store, especially amongst 

early varieties. 

Verticillium ? Apparently increasing ; responsible for local 

failure of crop. 

VEGETABLES. 
Bean. 
Pod Canker. Colletotriclmm Causes considerable damage in certain seasons. 

lindemuthianum 
Rust. Uromyces fabae . , ? 

Peas. 
Streak. Bacterial ? . . . ? 

Mildew. Erysiphe polygoni . ? 

Brassica. 
Finger and Toe. Pla-smodiophora Very considerable. 

brassicae 
Bacteriosis. Psextdomonas cam- ? 

pestris 

Celery. 
Leaf Spot. Septoria apii , . Considerable. 

Onions. 
Mildew. Peronospora schleideni Considerable in certain seasons. 
Sderotinia sp Locally responsible for serious damage. 

Tomato. 

Rust. Cladosporium fnlvum . Annually responsible for serious losses under glass. 

Potato Disease. Phytophtliora Responsible for decay of much fruit in the open. 

infestans 

Canker. Mycosphaerdla citrul- Very serious at a few centres in the past. At 

Una present almost absent. 

Stripe. Cause obscure . . Causes very serious losses in many parts under 

glass. 



CORRESPONDING SOCIETIES. 59 



Corresponding Societies Committee. — Report of the Committee, 
consisting of Mr. W. Whitaker (Chairman) , Mr. Wilfred 
Mark Webb (Secretary), Dr. F. A. Bather, the Rev. J. 0. 
Bevan, Sir Edward Brabrook, Sir H. G. Fordham, Sir 
Thomas Holland, Mr. T. V. Holmes, Mr. J. Hopkinson, 
Mr. A. L. Lewis, Mr. Thomas Sheppard, the Eev. T. E. E. 
Stebbing, and the President and Gener.\l Officers. 
(Drawn up hy the Secretary.) 

{The Committee held a special meeting on January 8, 1918, to con- 
sider the proposal to commandeer the British Museum and passed 
the following resolution, which was sent to Mr. Lloyd George, Sir 
Allied Mond, Lord Rothermere, and Lord Sudeley : 

' The Corresponding Societies Committee of the British Asso- 
ciation wliich represents provincial societies in the Kingdom 
with an aggregate membersiiip of 46,000 protests against the 
use of the British Museum including the Natural Histoiy 
Museum as Departmental Offices. 

' Apart from the damage to irreplaceable specimens which 
would result and the confusion which would be introduced into 
the whole collection, such a step would stop scientific work of 
great importance to the nation and essential to the successful 
prosecution of the War.' 

The Conference of Delegates will be held in the apartments of the 
Geological Society, BurUngton House, London (by kind permission of 
the Council), on Thursday, July 4. 

Dr. F. A. Bather will be President; Mr. Mark Sykes, Vice- 
President. 

At the first meeting the President will deliver his Address, 
entitled, 'The Contribution of Local Societies to Adult Education.' 
Upon this ,a discussion will be invited. 

Mr. B. B. Woodward, F.L.S., F.G.S., will exiiibit a Typomap 
of the British Isles, on which naturalists may i-ecord the distribution 
of species. 

The question of ' Grants for Regional Museums ' will be introduced 
by Mr. Percival Westali and discussed. 

At the afternoon meeting Mr. Martin C. Duchesne, F.S.I., will 
open a discussion with a paper on ' Afforestation. ' 

The Committee asks to be reappointed and for a gi-ant of 251. 



60 REPORTS ON THE STATE OP SCIENCE. — 1918 

Conference of Delegates of Corresponding Societies. 

The meetings of the Conference took place on Thursday, July 4, 
1918, at Burhngton House, London, by kind permission of the Geo- 
logical Society. At ten o'clock the President (Dr. F. A. Bather, 
P.R.S.) delivered the following address, entitled: — 

lUe Contribution of Local Societies to Adult Education. 

It is one thing to achieve greatness, another to have greatness thrust upon 
one. While I thoroughly appreciate the honour of being selected to preside 
over the deliberations of a Conference, which, let me mention, I first attended 
in 1881, yet I could have wished that the dignity had been thrust upon me 
at less short notice. With adequate time for the preparation of an address 
such as custom requires, I could Tiave pleased myself, if not my hearers, by 
unloading the burden of certain ponderings during these many years on the 
subjects prescribed by the Council of the Association as suitable for our dis- 
cussion. But in these days every man's time is filled, and you will readily 
pardon me if instead I ask your advice and help towards a Eeport which 
I have been asked to draw up for another committee. 

The subject of the desired Report is ' The Extent and Scope of the Work 
of Naturalists' and similar Societies up and down the country ' in special refer- 
ence to 'non-vocational adult education,' or, as I have phi-ased it for our 
purposes, ' The Contribution of Local Societies to Adult Education.' 

Tlie reference admits of some latitude in the interpretation of the term 
Local Societies. As regards restriction of place, a rigid interpretation of 
the word ' local ' would exclude not only such bodies as the Royal, the Linnean, 
and the Geological Societies, but also the Selborne Society and the Museums 
Association. This would be a mistake. Again, a society must not be excluded 
because its headquarters are in London, or even because it has a Royal Charter. 
The Geologists' Association is confessedly an educational body for amateurs. 
The most obvious activity of the Zoological Society is the education of the 
populace. Some meetings of the Royal Geographical Society and the lectures 
of the Royal Institution appeal intentionally to those who are not professed 
students of science. 

As regards restriction of subject, the bodies to be discussed are in the main 
societies for the promotion of natural history studies, but include a considerable 
number which devote their attention in large part to other branches of physical 
science, to archaeology and history, and even to philosophy and polite literature. 
The line between naturalists' societies and the others is vague and fluctuating, 
and the name is often an unsafe guide to classification. A society with the 
words ' natural history ' in its title may drift into archfeology and stay there, 
perhaps half-a-century, till some prophet of nature arises in the neighbourhood 
with force enough to re-introduce the old studies. 

Probably every district has the societies which it needs, and if people pi-efer 
one subject rather than another they are only to be commended for cultivating 
it. The educational effect depends less on the subject than on the way in which 
it is approached. Our ultimate classification will therefore be based on method 
rather than on matter. 

In compiling my own list I have excluded societies for the propagation 
of the Arts and Crafts, Photographic Societies except when they conduct 
regional surveys, and pui'ely literary societies such as tlie hundreds of Shake- 
speare Societies. Some societies that do not, at least in their titles, claim 
connection with natural history or with science of any kind have been included 
because the papers read before them occasionally deal with the facts or theories 
of Natural Science. 

To appreciate the educational influence of these societies we have first to 
consider their number, distribution, and strength. 

For nearly forty years the British Association for the Advancement of 
Science has attempted to draw to its bosom some if not all of those societies 
scattered throughout our islands which promote any branch of knowledge that 



I 



CORRESPONDING SOCIETIES. (.jl 

comes within the piuview of the Association itself. These Correspondin' 
Societies are <Iivi<led into two classes : (1) Those which ' undertake local 
scientiBc investigation and publish the results.' These are Affiliated Societies. 
(2) Those which ' encourage the stu<]y of Science,' as opposed presumably to 
investigation, and (it is implied) do not publish results because they have none 
to publish. These are Associated Societies. 

For our present pui-pose the distinction drawn by the British As.sociation 
between Affiliated and Associated Societies does not greatly trouble us. Indeed 
a society that ' encourages a study,' even though it refrain from publication, 
may be doing more educational service than a small body of professional investi- 
gators publi-shing technical papers and making no appeal to the public. 

In 1883 the number of ])ublishing societies regarded as worthy of admission 
was 175 for the whole of the British Isles. This number included the Cumbei-- 
land Association, the Midland Union, and the Yorkshire Naturalists' Union, 
which three bodies represented 70 eocieties. Twenty of those societies were 
also in the general list, so that the number of presmnably non-publishing societies 
comprised in the Unions for about half of England alone was 50- Considering 
the difficulty, then as now, of obtaining information, we may say that for 
the British Isles at fhat date a total estimate of 200 publishing and 200 non- 
publishing active societies would probably have been within the mark. The 
number of 31) actually placed on the roll of Corresponding Societies in 1885 
therefore represented about one-tenth the total number and one-fift'h the admis- 
sible number. This was good enough for a beginning, but, as expounded 
in Sir George Fordham's Address to the Conference of Delegates in 1914, the 
number did not increase materially till the widening of the entrance qualifica- 
tions in 1905, when lie records a total of 72. High-water mark, according 
to Sir George, was reached in 1912 with a total of 114. 

Last year, 1917, the numbers were : Affiliated, 88; Associated, 32; total, 
120. But of the Affiliated .Societies two were outside the British Isles. 

This, however, gives a most imperfect idea of the total number of eligible 
societies in these islands. It is not easy to estimate what that number may 
be, but I have made an attempt. Taking all the lists available, such as 
Griffin's 'Year-book of Scientific and Learned Societies,' the Catalogue of 
the Natural History Museum Library, the lists of the Unions, and the ' Museums 
Directory,' I have compiled a card index. It contains 392 names. But even 
this is certainly incomplete, as will appear from various considerations. For 
instance, I was able to .supplement the aforesaid published lists from my own 
personal knowledge, and no doubt other people could in the same way supply 
names of other societies which ought to be in these lists. 

Another line of argument is derived from the geographical distribution 
of the societies listed. This is shown on a map exhibited here. Two facts 
are manifest on this map. One, the extensive areas without any indica- 
tion. Some of these are due to paucity of population, but others must be 
assigned as much to our own ignorance as to any lack of interest on tlie part 
of the inhabitants. That I ihave been able to credit certain districts with a 
goodly number is due to the existence of Unions, such as the Yorkshire 
Naturalists' and the Sonth-Eastern, which have swept a large proportion of 
the societies into their lists. It is only such lists that have told me of the 
continued existence of societies which for years had given to the outer world 
no sign of life. Where Unions have lapsed, as in the case of the Midland 
Union, or have never existed, as in S.W. England and East Anglia, our 
information is undoubtedly deficient, probably by at least one-half. Tlie second 
fact that emerges is the congregation of the recorded societies in or near tlie 
great cities. Greater London finds room for about 50, Manchester 13, Liver- 
pool 11, Glasgow 7, Edinburgh and Dublin 8 each, Leeds 9. The region round 
Bradford, Halifax, and Huddersfield, 14 or 15. It was here that the York- 
shire Naturaliists' Union came into being, with its constituent societies each 
within a walk of the others. Newcastle, Carlisle, and Worce.ster have C each : 
Hull 5; York, Birmingham, Bath, Norwich, and Southampton are each credited 
with 4. This makes 158 out of our 392. Partly this concentration is due to 
density of population but not entirely. Something is due to f.ashion : B«th, 
for instance, has a reputation to keep up. But a good deal is due to the 

1918. *■ 



62 REPORTS ON THE STATE OF SCIENCE. — 1918. 

publicity attending such efforts in these places. One society joins a Union 
and the rest follow. There are certainly societies in many a town that is 
not so marked on the map, but they live a life apart, and we hear nothing 
of them. Instances of this are Lancaster, Wolverhampton, Coventry, Lich- 
field, Colchester, and Salisbury — each of tliem 'no mean city,' and probably 
boasting more than one scientific society. 

Taking all these facts into consideration, I am convinced that our list 
might be increased to 500 or 550 without losing its character. 

But this is not all : widely though the net may be cast there are a number 
of societies carrying on educational work of considerable value, yet too small 
or obscure to be caught in its meshes. Any estimate of their number must 
be quite vague, and yet it is worth attempting if one wants a true picture 
of the state of the country. Take the Borough of Wimbledon with its popu- 
lation of nearly 60,000. In the list as compiled there are only two societies 
entered, of which one is associated to this Conference. There are, however, 
six others known to me as doing good educational work. It is quite likely 
that the same proportion obtains in many other towns. The inclusion of such 
societies in our list would raise the number to at least 1,000. 

We may pause here to consider wbetlier it would not be advantageous for 
us to bring more of these societies within our fold. In the early days of this 
Conference the conditions of admission included local scientific investigation 
and the publication of results. Since the delegate became ex-officio a member 
t)f the General Committee a reasonably high standard was certainly desirable. 
Now that the rule of 1905 admits non-publishing societies as as.sociates, with- 
out representation on the general committee, we should make more etrenuous 
efforts to obtain their co-operation. Even on the ground of investigation, the 
publication of a report is no criterion of the value of the society. The con- 
tents of the report may lack originality, and, on the other hand, the members 
may do excellent work but prefer to publish in some other form than a special 
organ of their own. This is recognised by the S.E. Union, which compiles 
and publishes a list of such papers produced by its members. The multipli- 
cation of trivial Reports and Proceedings is not an umnixed blessing to anyone 
except the printer, and I long regretted that the British Association should 
have felt obliged to make this a test for admission. 

Our object is to encourage and co-ordinate the work of local societies, 
aiid we cannot do this effectively so long as we remain out of direct touch 
with 88 per cent, of them. Perhaps the conditions of membership might be 
eased by making it possible for a society to become a member of the Association 
by compounding for a term of years, on the principle of the life member. 
Especially in present circumstances we can hardly expect individuals or societies 
to pay a pound apiece for the privilege of some five hours' attendance at this 
Conference. But if a society could secure representation for 30 or 40 years 
by a single payment of 10/., this would be an inducement to it to send a 
delegate, and to continue its activities sufficiently to conform to our standard. 
On the other hand, the attendance of a delegate at the Association meetings 
and at this Conference would, let us hope, react favourably on the Society. 

Hitherto I have considered only the number of societies. It may be worth 
vdiile to estimate, however roughly, the number of individual members. Taking 
our own list for 1916 and excluding the associates of the large Unions and 
the membeit) of the oversea societies, we find 88 Affiliated Societies with a 
•total membership of 22,535, or an average of 256; and 31 Associated Societies 
with a membership of 7,079, or an average of 228. The total average is about 
248. This number is, however, liable to correction, because in most of the 
larger societies a considerable pi'oportion of the members are also members 
of other societies in the list. Also it is hardly fair to reckon as characteristic 
the Institution of Mining Engineers with its 3,600 members. Probably it would 
be fair to take 200 as the average number of members in a society of the 
kind we are considering. Certainly if we include all our supposed thousand 
societies, this would not be an undei'e«timate. That gives a grand total of 
200.000 individual members for the British Isles. From one point of view, 
a respectable number ; but in reference to the whole population of forty-five 
millions, only 0*4 per cent. 



CORRESPONDING SOCIETIES. 63 

Fortunately the educational influence of our societies is not confined to 
their actual members. Often it reaches a large proportion of the surrounding 
population. Let us now turn to this aspect of our subject and see how the 
societies work. In a sen.se all their activities have an educational bearing, 
but some act more directly than other-s. The chief of these are Lectures^ 
Excursions, and Museums. 

At our Newcastle Conference (1916) the subject of Lectures was dealt 
with in so admirable a manner by Mr. Percival Ashton in his paper and 
by Professor R. A. Gregory in the Interim Eeport of the Committee on 
Popular Science Lectures ' that it is impossible for me to add anything. 
Only for the sake of reminder I would emphasise this point. A distinction 
must be drawn between lectures to the society and lectures b]/ the society. 
The society presumably consists of persons who, if not already learned, at 
least are prepared to learn. They lend a ready ear, and need no argument 
to convince them of the interest or utility of the studies which they have 
themselves combined to promote. Befoi-e suc'h an audience the lecturer starts, 
without apology, in the middle of his subject. Lectures arranged by the 
society for an outside public stand on a different footing. They must be 
attractive and attractively advei-tised. The lecturer has to make good, to 
persuade, to convince. The former class of lectures may profitably convey 
definite instruction ; the latter class should be rather in the nature of pro- 
paganda. They may afford a glimpse of the marvels of science or the 
fascination of the natural world, but their most useful service at the present 
day will be, in the words of the above-mentioned Report, ' to show as many 
people as possible that they are personally concerned as citizens with the 
position of science in the State, in industry, and in education.' The Eeport 
spoke of the hostility or unreceptiveness of the general public towards science. 
This attitude, and the equally distasteful one of a jesting tolerance, have been 
greatly modified by the war. Now is our great opportunity. The scientific 
principles at the base of food, of agriculture, of nninitions, and the like 
urgent problems are no longer despised. The treatment of the wooiided, 
protection against vermin and insect-borne disease, and the care of children afford 
many openings. The historical background of the war, the ethnology of 
Central Europe and the Balkans, the influence of language, the nature of 
frontiers : these are questions that have a less insistent appeal for the 
multitude, but they will find their audiences all the same. There is scarcely 
a branch of human knowledge and mental activity that has not been stirred 
into new life by the present struggle. Our societies must be ready to take 
advantage of this ferment, so that on the advent of peace the public mind 
shall not revert to its old stagnation. 

The second educational method is by Excursions. Under this head are 
included visits to natural objects, to antiquarian remains, to zoological and botani- 
cal gardens, and to museums of science or of art. These are as a rule but lectures 
in another form ; at any rate they are demonstrations. They are confined to the 
members, as a rule, but they usually prove more attractive than the indoor meet- 
ings, and so swell the ranks by introducing folk who come first for amusement but 
may remain for instruction. 

Of a more serious character are those field excursions on which some acinal 
work is done. Either specimens are collected and records noted, as on the 
jjopular Fungus Forays, or a systematic survey is conducted. As typical of 
a body undertaking such work, one may instance the Yorkshire Natuialists' 
Union. In a Presidential Address to that body in 1904, Mr. W. Denison 
Roebuck- said: 'Our tnie function is not an educational one. but one of 
original research at first-liiand, and the publication of residts. The only 
educational aspect of our work is that in which the observer teaches himself 
by his observations, and in which original workers influence each other. We 
leave the task of training the recruits from whom future observers will arise 
to the schools, colleges, universities, who are better equipped for such ;v 
task. It is our business to observe facts . . . and to place them on record . . . 

» Rep. Brit. A.ssoc. 1916. pp. .326-351. 

2 1904, Trans. Yorksh. Naturalists' Union, Part 35, p. 14. 

f2 



64 REPORTS ON THE STATE OP SCIENCE. — 1918. 

and particularly it is our function to preserve the field-naturalist observing 
the inter-relationships of natural phenomena in the open, rather than the 
technical operator working in the laboiatory. ' I do not think that Mr. Roebuck 
need have been at such pains to disclaim the educational value of this work. 
There is no better training for a naturalist than observation in the field, 
and presumably even the members of the Yorkshire Naturalists' Union aro 
not all ready-made experts. Even if they have to pass an examination before 
being given a member's card, still nature transcends any teaching and the 
more one's circle of knowledge spreads the wider are the limits to the unknown. 
No education is more solid and permanent than one founded on a first-hand 
acquaintance with hard facts, in the field no less than in the laboratory. 
If our societies wish to increase their educational force, let them follow 
ths example of their' Yorkshire colleagues. 

The third and last of the methods by which our societies work is the 
establishment and care of Museums. Some societies exist for this purpose 
alone, as the Norwich ^luseuni Association arrd the Horsham Museum Society. 
Others have always regarded it as a primary function ; such are the Ludlow 
Natural History Society and the Whitby Literary and Philosophical Society. 
Others agairr have begun with the collections accumulated by members, have 
gradually formed these into a private museum, therr have thrown this open 
to the public under gradually diminishing restrictioirs, and finally have trans- 
ferred the whole to the town, either with the retention of a share in its 
government or completely. Such was the history of the Thurso Public Museum, 
founded by the Thurso Natural Science Association, and of the Dudley 
Geological Museum formed by the Dudley and Midland Geological Society. 
Whether as cause or consequence of relinquishing their museums, these two 
societies are now dead. Irr my list there are iro less thair 52 societies — more 
than a quarter' — now actively responsible for museums, and iir some cases 
museums of great reputation. Still more societies have their headquarters at 
museums, and of terr help in the museum work. While it is well that museums 
should be placed on such a sound financial footing as a municipal rate can best 
supply, still it is desirable that an intimate connection should be maintained 
between the public musermr or museums of a town and the various local 
societies. As an educational instriiment the museum, if properly managed, is 
unsurpassed. Like the field and the laboratory it teaches by concrete objects, 
which make a more vivid impression than the word.s of a book or lecture. 
The lecture is only for one brief hour, the excursion demands an occasional 
holiday, but the museum teaches all the time. The museum fonns a centre 
for the members of the society, serves to attract fresh members, and by 
its varied exhibits and special exhibitions should be making an ever fresh 
appeal to one or another class of the neighbouring population. But to this 
audience I need not emphasise the educational value of a properly conducted 
museum. All you have to do, if your society maintains a museum, is to 
see that it does conduct it properly. If you do not know what that means, 
come on to the Conference of the Museums Associatiorr and we will tell you. 

I have purposely given a mere sketch of these educatioiral activities, for 
it is waste of breath to preach to the converted, and on this occasion it is I 
who wish to get advice from you. I may fittingly conclude with an extract 
from the Report of the South-Eastern Union for 1917 : ^ ' We believe that 
one result of the war will be a stirring up of educational enthusiasm and 
activity, both nationally and locally. The S.E. Union of Scientific Societies 
and its individual affiliated societies are educational institutions. Each society 
can do much within its own area to quicken local interest in the geography 
and geology, the fauna and flora, the history and antiquities, and in the 
immediate and future civic problems and possibilities of the district.' 

Yes — we can all do this, if we will oirly recognise our powers. And in 
these days, when one has powers of this kind it is a duty to exercise them. 

Sir Edward Brabrook (Balham and District Antiquarian and Natural 
History Society, and Lewishanr Antiquarian Society), in proposing a vote 
of thank', to the President, said that he spoke both as founder and first 

' S.E. Xaiiiralist, p. xxiii. 



CORRESPONDING SOCIETIES. 65 

President of the two Associations which he represented, and he claimed that 
they had done what was in their power to form an educational centre in 
their distric-t of London, and in one direction they had so successfully educated 
their members that quite a number of them had sought and obtained fellowship 
of the Society of Antiqiiaries. 

The phase of education to which the President had particularly directed 
their attention was that of the education of the general public. The onlv 
point in which they had perhaps failed in their original intention, to his 
mind, was, that they began with the idea of combining Archieology or 
Antiquarianism and Natural History, and that their contributions to Natural 
Histoiy had been very slight, and practically they had abandoned that brancii. 
He was sorry that it was so, but it could not be helped ; a different people were 
interested perhaps in Archreology from those who were interested in Natural 
History. 

He thought that in striking an average of 200 as the membership of local 
societies the President had erred in excess. 

Mr. W. \Vhit.\ker (Essex Field Club), who seconded the vote, urged that 
in estimating the value of societies they must not be led astray by numbers ; 
they should consider the proportion of working members. On the question 
of lectures, those ' to ' the Society were supposed to instruct, not only the 
societies, but the inhabitants generally, and very often these lectures were 
more or le.ss open — even free, or foi" some .'(light payment. The primaryi 
object of local societies was to deal with more local science ; their next duty was 
to spread abroad that knowledge. That was where the educational part came 
in. They could not, however, do that until they had started the first. Then 
another way in which local societies might do good in their neighbouihood 
in an unpretentious way wa« by helping the schools. Schools would be glad 
of assistance as to the fauna and flora of their districts. He was speaking 
now of pupils being taught something of their surroundings. It was a teaching 
that appealed to those who were taught. He had the pleasure of doing 
something of the sort himself. For instance, he had fifteen oi' sixteen girls 
from a school as an audience over Hampstead Heath. They really appi'eciat^d 
seeing things and having them explained, and he was told by one of their 
teachers that they had investigated for themselves and they wanted to see 
what there was under the soil. If you could get a spirit of that sort in the 
schools it would grow. It gave an appetite that would increase, a healthy, 
wholesome appetite. There was, further, the effect of this work on 
the teacher. Some teachers were apt to forget that those they taught had not 
the knowledge they had themselves. Taking the children out brought them 
into more intimate contact with those they had to teach; they got a better 
idea of what to teach and how it was to be put. 

In museums it was very important that local societies .should get into touch 
with the local authorities. His idea was, that in large places there should be 
some meeting-place belonging to the local authority, where not only their 
natural history societies but other public societies and public bodies should 
have some sort of resting-place or meeting-place. 

However humble their societies might be, they might and should exercise 
a considerable influence on the educational work of our country. 

Mr. Robert Cockburn Miller (Edinburgh Geological Society, and 
Edinburgh Field Naturalists' and Microscopical Society), who gave a li.st of 
the societies of Edinburgh, said that one of the difficulties that they had 
— and he could speak as a contributor to several of the societies for many 
years — was that of funds. The subscriptions were small, and in these days 
the publication of ' Transactions ' cost a good deal. It was a curious thing 
that, while there were charities of all kinds, there had been wonderfully little 
contributed to these societies, although they had done an immense amount of 
very valuable work. 

With regard to the subject of the President's paper, he said that a field 
naturalists' society which was in the fiftieth year of its existence had a very 
large number of members who were engaged in teaching, and it was very 
encouraging to see the enthusiasm of these teachers in finding some new kind 
of plant or animal, and in ascertaining from the others, or else from the 



66 RKPORTS ON THE STATE OF SCIENCE. — 1918. 

books which they carried with them, all that could be known about it. Con- 
stantly, also, one heard them mention that they encouraged their scholars to 
bring them specimens of things that they themselves could not find. 

Several parts of Scotland had excellent museums ; he would not mention 
names, because they were so numerous. In regard to illustrations of birds 
and bird life, Mr. Miller intimated that pupils brought specimens, but that 
they had been distinctly told that ther'e must be no destruction or cruelty 
in providing them ; that where this condition was fulfilled the museums were 
glad of the specimens. 

Mr. !Miller went on to say that corporations and other local authorities did 
take an interest in local societies, and in Edinburgh their Geological Society 
was now housed in the Corporation buildings. Again, corporations could mark 
interesting features. They had several examples in Edinburgh ; for instance, 
at a place where Agassiz had stayed. 

On the popular educational side, !Mr. ]\Iiller mentioned the work of one 
scientific man who took an interest in the education of adults. They had in 
Edinburgh for many years, John George Goodchild, who was a member of 
most of the societies, and he used to gather round him as many of the people 
as he could get and demonstrate at the museum, or take them into the 
country and show them different things. He remembered many instances which 
pointed very strongly to the value of these excursions as enunciated by ]\Ir. 
Whitaker. 

The Rev. J. 0. Bevan (Woolhope Naturalists' Field Club) maintained 
that it would be a most desirable thing if those associated with their local 
societies would pay more attention to the schools, and get the interest of 
the head and assistant teachers enlisted in their subjects. No doubt one great 
difficulty in securing systematic instruction would be the provision of suitable 
teachers, and local societies should take pains to ascertain the local conditions, 
and do what they could to further the provision of proper teaching and 
fa<;ilities. 

Mr. J. HoPKiNSON (Hertfordshire Natural History Society) agreed with 
the President in drawing a distinction between paiblishing and non-publishing 
societies, and that the authorities of the Association were quite right in giving 
a higher status to the former. In Hertfordshire they had far more good papers 
than they could afford to publish : they had to cut them down, and decline 
some. They had not for .some years printed a single paper which had not 
been the result of local investigation, or did not instruct others how to make 
local investigations. 

It was only in our large towns that a society could afford a museum. 
Their museum at St. Albans 4iad a grant from the County Council of 150/. a 
year ; the rest of the funds being contributed by subscriptions. He knew 
the museum was doing good educational work, especially among children, and 
it was visited by people not only from distant parts of this country but also 
from abroad. 

^Ir. J. Wilson (Quekett Microscopical Club) said they published ' Trans- 
actions ' which were lai'gely quoted. They had various collections of 
microscopical specimens, and the Club, with its discussions, was largely taken 
advantage of by local members. During the last four years members of 
the Club to the number of a hundred had gone from eight to ten in the 
evening almost every day of the week, to give lectures to soldiers and sailors 
at various headquarters, and these lectures had been appreciated. 

Mr. T. Sheppard (Hull Scientific Society) said he had developed from 
one of the most optimistic into the most pessimistic of men bec-ause he was 
afraid that the interest in scientific work was decreasing, and something 
would have to be done to incriease it. In what they had done in his own 
county, or the eastern part of it, it looked as if they were going to natural- 
historyise the whole population. But the extraordinary result was, they had 
less people taking an interest. In the old days when they had classes they 
had twice or three times the membership in their societies that they had 
now. Another thing he was a little pessimistic about was the way in which 
their British Association for the Advancement of Science — the one institution 



CORRESPONDING SOCIETIES. (J? 

which existed for that purpose — should have set them the example of not 
having an annual meeting. There was absolutely no excuse foi' not having 
a meeting in that or some other room in London. 

j\ir. W. Whitaker supplemented his remarks by saying that local societies 
might help in the formation of libraries. Their societies could help in filling 
up ligts of scientific works in their localities. There must be many men whii 
had numbers of books that they did not specially want. It would be vei-y 
much better to do distributing work in their lives than to leave it to their 
executors to deal with, and it would be a good thing if they handed some 
of their well-collected scientific literature to some public museum or libi'aiy 
in their neighbourhood. Libraries were one of the chief means of furthering 
education. 

Miss jMargaeet C. Crosfield (Holmesdale Natural History Club) spoke of 
a revival of interest in her neighbourhood, where the school teachers wei'e 
entering into the work and spreading it among the children. They had 
admitted teachers into their society on special terms — a special subscription of 
half-a-crown. 

Mr. Whitaker interpolated that the same was done at Croydon : teachers 
were admitted at half subscription. 

The President thanked the speakers for the many suggestions made, some 
cf which probably would find a place in his Report. The influence of their 
societies in teaching teachers of course was a very important one. In regard 
to this there was the difficulty teachers had in getting away to excm'sions. 
It was just conceivable that if one could emphasise the value of the work 
of these societies, acting through the teachers, to the children, some influence 
might be brought to bear on the educational authorities to facilitate the 
attendance of teachers at excursions in school hours, in the same way as 
in some places visits to museums were reckoned as part of the educational 
course. 

What ^Ir. ^Miller had told them about Edinburgh reminded him of 
the public labels he had been pleased to observe at St. Albans. Local societies 
should bring influence to bear on their municipalities to allow them to put 
up tablets on historic buildings, and so on, in a conspicuous and artistic 
manner, which would be of great advantage to the public and to themselves, 
but they must not rely too much upon these corporate bodies. The. old sign- 
boards put up all over the coimtry by the Cyclists' Touiing Club were most 
valuable, but when this work was placed in the hands of County Councils, 
for some years one found these old boards of the C.T.C. gradually falling into 
decay and nothing to replace them. Anybody who cycled about the country 
found great diversity in the counties. These were matters in which such 
societies as theirs could bring a certain amount of influence to bear on those 
public bodies. 

He thought perhaps on the general question the most important remarks 
were those contributed by Mr. Sheppard. His were another example of the 
fact that people valued most what they had to take most trouble to get and 
what they had to pay for. Another cause of the lamentable results to which 
Mr. Sheppard referred might perhaps be that the interest excited by museum 
visits had nothing continuous about it : they were perpetually interesting people, 
but they were not leading them on. To get permanent results, the mueeum 
curator should give the children facilities for continuing the study of any 
subject in -whieli he found that their interest was aroused. One must not, 
however, demand too much from the musemns ; it does not in the least follow 
that a boy who takes an interest in history, ie going to be an historian ; it does 
not follow that because a boy has taken interest in geological specimens he is 
going to become a geologist; only, if you want him to follow up a special subject, 
he must not be taught in a scrajypy way. 

The Report of the Corresponding Societies Committee was read by the 
Secretary and it was agreed that the Council of the Association be requested 
to appoint Mr. Mark Sykes a member of the Committee. 



68 REPORTS ON THE STATE OF SCIENCE. — 1918. 

Kent's Cavern. 

The question of Kent's Cavern was raised by Mr. Bevan, and after some 
discussion he proposed a resohition to the effect that the Council be asked to 
appoint a Committee consisting of Mr. William Whitaker, Mr. Mark Sykes 
and Mr. Wilfred Mark Webb to deal with the matter. This was seconded 
by Mr. T. Sheppard and carried. 



The second meeting was held at 2 p.m., and Mk. Martin C. 
Duchesne staiied a discussion with the following paper upon: — 

Afforestation : Its Practice and Science. 

Introduction. 

Afforestation — a life-long interest to a few — until recently was little more 
than a word to t)lie average politician and the public. The war, however, 
has opened many eyes to the grave and pressing importance of an assured 
oational timber supply. My object is to emphasise this importance and to 
bring out the need also for closer association of science with practice in building 
up our future timber reserves. 

The case for afforestation was strong before the war, but actual war experience 
has made it overwhelming. Our imports of timber, amounting to Sg cubic 
feet per head of ixipulation in 1851, had steadily increased to 10-^ cubic 
feet per head in 1911. Meanwhile the home supplies had deteriorated. The 
United Kingdom, caught without sufficient home reserves, had to continue 
importing timber on a large scale at any expense. The costs were enormous, 
involving (1) an additional expense of nearly 40.000,000/. above the pre-war 
prices for necessary supplies of timber during only the first tivo years of war ; 
(2) absorption of tonnage urgently needed for other purposes; (3) loss of cargoes 
sunk by the enemy; (4) depreciated exchange. In our extravagant reliance 
on imported timber we ran risks, as the recent Forestiy Report reminds us, 
' against which every other considerable countrv has long taken care to protect 
itself.' 

National Timber Demands. 

Up to comparatively recent times the national importance attached to timber 
was confined almost to Ihe provision of oak for the Navy and wood for fuel. 
These demands have been supplanted by others, and the problem of oak for 
the Navy is replaced by that of props for the mines and timber for national 
industries and uses. Building, constructional, and transport trades demand 
limber in vast quantities. As a munition — for aeroplanes, army wagons, 
artillery spokes, sleepers, huts, ammunition boxes, shipping, railway and trans- 
port purposes, trenches, fuel, and in many other directions — timber has never 
been so indispensable as in this war. For national reconstruction purposes — 
not only here, but also with our allies, especially in the devastated areas — 
the demand for timber will be very gieat. 

The Coast Erosion Commission, in 1909. recommended afforestation of 
9,000,000 acres to make the countiy independent of foreign supplies. The 
Government reply was the creation of the Development Fund, which we were 
promised would do much for forestry, but which has been a severe disappoint- 
ment to all parties. With our 3,000,000 acres of woodlands, we are still, 
with the exception of Portugal, the vs^orst affore.sted nation in Europe. 

The need — great in any event — for a comprehensive scheme of real encourage- 
ment to forestry the war has now shown to have very vital relation to the 
safety of the realm. 



CORKESPONDING SOCIETIES. 69 



The Forestry Report. 

In the Final Report of the Forestry Sub- Committee of tlie Eeconstruction 
Committee the proposals now under Government consideration are developed. 
These proposals represent a basis for State afforestation combined witli 
encouragement to private enterprise. 

To account for the poor condition of our woods, the Forestry Report refers 
to the fall in value of small hardwood timber and oak baxk, the increased 
demand for coniferous timber, old and unsuitable methods of management, game 
preservation, and love of the picturesc|ue. In my opinion the most serious 
causes have 'been omitted, namely : 

1. ITie agricultural depression of the past generation, which denuded the 
countryside and dhilled the spirit of enterprise. 

2. The glutting of the home timber markets with the produce of the world's 
virgin forests at prices that very often represented little beyond the cost of 
felling, transport, and marketing, in addition to importers' or agents' profits. 

3. The unfair handicaps from which forestry suffered, and to which I refer 
later, and the neglect of the State, shown by the absence of mn/ endeavour 
to remove those handicaps. 

4. An absolute indifference to forestry and lack of encouragement of native 
timber by the consmners of timber, by industrial concerns, by the Government 
departments, and by all sections of the connnunity. 

Absence of well-managed State or Crown forests in the past is rightlj- noted 
as a drawback to the private owner, who had nothing to guide his efforts at 
timber production by the system of High Forest, comparatively new to this 
couutrj\ He had to |)iok up knowledge as best he could, buy his exi)erieiice 
as to trees to plant and incur sad losses. 

The proposals of the Forestry Report include planting 1,770,000 
acres in addition to replanting and improving existing woods, with 
the object of making the United Kingdom independent of imported 
timber, in emergency, for three years. This moderate requirement, however, 
is subject entirely to satisfactory arrangements being made with Canada, which 
' contains the only large reserves within the Empire.' Failing such arrange- 
ments, the Report admits that a much larger scheme will be neces.sary for 
the Unite<l Kingdom, owing to the precarious nature of foreign supplies, com 
bined with their steady rise in price. 

I would submit that a larger scheme — based on a five years', in place of 
three years', emergency i-eserve of timber — is now necessary for the following 
amongst other reasons : 

1. The Forestry Sub-Committee was appointed in July, 1916, and since 
their Report was prepared there have been large and unforeseen developments, 
including : 

(o) The ' break-up ' of Russia and the existing uncertain position in 
that country and the Baltic, on which sources we have relied in the 
past for over 70 per cent, of our timber supply. 

(6) Further vast quantities of our native timber have been felled, 
as compared witli the quantity mentioned at the date of the Report. 

2. The war goes on indefinitely, with demands accumulating, and if this 
wai" lasts nearer five years than three, surely a five years' reserve for the 
future should be assured. 

3. The developments in the air and under the sea even in the near future 
ar.> impo.ssible to e^stimate; our reliance on shipping is more fully appreciated 
and it« resources must not be taxed by timber transport in an emergency. 

In view of the national importance of the creation of reserves of timber to 
meet ony future emergency, I hope that an extended scheme will be instituted. 

The general case for afforestation in the Report is based on these three 
propositions : 

1. That dependence on imported timber is a grave source of weakness in 
war. 



70 REPOKTS ON THE STATE OF SCIENCE. — 1918. 

2. That our supplies of timber, even in time of peace, are precarious and 
lie too much outside the Empire. 

3. That afforestation would increase the productiveness and population of 
large ai-eas of the British Isles which are now little better than waste. 

Preliminary to afforestation schemes is the creation of a Forest Authority, 
to whom details as to afforestation must be left for decision. 

As to afforestable land the Forestry Report estimates that the United 
Kingdom contains between four and five million acres of rough and waste 
land from which to select the area required for afforestation. 

Tlie association of small holdings with forestiy is advocated by the Forestry 
Report because forestry combines so well with, agricultui'e. 

The encouragement suggested for private planters includes a possible reduc- 
tion of assessments for rates and taxes, and the abolition of extraordinary 
traffic is recommended. It is proposed that the Forest Authority should be 
empowered to confer with the railway companies to obtain a reduction of rail- 
way rates. Suggestions are made for the organisation of the home timber 
industry and the development of woodland industries. Financial proposals 
include optional fomis of assistance which might be offered to landowners, 
including either : (1) State sharing expenses and proceeds, or (2) State making 
grants or conceding loans at low interest, or possibly (3) Landowner to be 
relieved from rates and taxes on the afforested land for an agreed number 
of years It is suggested that an owner who wished to regain control of his 
woods might do so by repaying the amount of the State contribution, plus com- 
pound interest. 

As to forestry organisation, references are made to: (1) pressing on 
forestry surveys and taking stock of existing woods ; (2) provision of seedlings ; 
(3) training of forest officers and men; (4) research and experiment; (5) advice 
on forest management ; (6) forest pests. 

The only forest pests inferred to are the pine weevil and pine beetle. The 
Forestry Report suggests that the Forest Authority might ' issue and enforce 
orders calling on owners of woodlands to take definite steps for dealing 
effectively with such pests.' You will note that there is no suggestion for 
the State to do anything but compel others to incur expense for the benefit of 
the community. 

I would respectfully submit that the State and others have obligations as 
well as the landowner. It is for the State to give a lead in proof of a 
sincere desire at last to encourage forestry. Before calling upon others to deal 
effectively with insect pests, it is surely for the State to make proper grants 
for education and research in these directions, and first of all to point out a 
practical and economical method of dealing with such pests. 

(Constantly we are reminded of the obligations and responsibilities of the 
landed interests. 

Has the State no Obligation to fulfil ? 

Has the consumer of timber in any industrial undertaking no obligation 
or responsibility to encourage native production of the raw material he uses ? 

Has the pulp manufacturer and newspaper proprietor no responsibility or 
obligation to encourage the demand for and creation of reserves of spruce and 
other pulp- wood in this country ? 

Have the railway authorities no obligations with reference to reasonable 
rates for the transport of timber, or the highway authoiities for proper 
facilities for carting timber over their roads ? 

Are the innumerable users or artisans who rely on timber either for their 
trades or their homes under no responsibility or obligation to encourage native 
forestry ? 

Have not the general public, who not only enjoy the woodland scenery of the 
countryside but also have an interest in timber as an important raw material 
for the safety of the realm, an obligation to support and encourage forestry ? 

It would have been possible for them to encourage private enterprise without 
making large demands on public funds, but their past indifference has been 
complete. 



CORRESPONDING SOCIETIES. 71 

Since real progress in forestry is impossible until the handicaps are removed, 
I may be pardoned for referring in detail to them. 

By their removal real encouragement will be given to piivate enterprise 
and estate forestry. 

Private enterprise and voluntary effort are as British as dependence upon the 
State is German. 

Let us now consider for a moment 



The National Importance of Estate Forestry. 

State operations must be limited principally to large areas and to waste 
and hill land. Better soils and smaller areas must be left to private enterprise. 
Estate forestry enjoys the following principal advantages : 

(1) It can ensure the necessary reserves of timber at least cost to the 
country. 

(2) It can plant the smaller areas. 

(3) It can plant the better soils and areas near urban and industrial centres. 

(4) It can grow ash and other valuable hardwoods on the better soils, whereas 
the waste areas and hill lands will be limited principally to conifers. 

(5) It can combine various "branches of agriculture with forestry to great 
advantage and provide wint^er work for those engaged in agriculture at other 
seasons. 

(6) It can gi'ow willows and other trees on short" rotation.s and so encourage 
rural industries. 

In the past estate forestry has received no assistance of any kind from 
the State. It is due to the patriotism of private owners — who planted and 
kept up their woods in spite of all the difficulties and handicajxs — ^that reserves 
of native timber have been available which have been of great value to us in 
this war. I trust that this fact will be recognised to the extent of removing 
the following handicaps : 

1. 2'ransiiort. — High and often prohibitive railway rates are a grievance 
of old standing in British forestry and if not corrected will prejudice the 
whole future of afforestation. In few districts in Great Britain has the timber 
been able to reach its proper and best markets, owing to the high railway 
rates. 

2. ' Extraordinary ' Traffic. — Timber pays towards the upkeep of the high- 
ways throughout the pei-iod of its growth. Yet it is liable to pay a further 
large sum when it is felled for damage to the roads incuiTed in its removal. 

3. Mates and Taxes. — The Agricultural Eates Act does not apply to wood- 
lands, therefore when an owner plants agricultural land he is immediately 
penalised. Death duties have had a detrimental effect, and both rating and 
taxing authorities have done much to discourage foi'esti-y. 

4. Markets. — The consumer of timber offers no encouragement of any sort 
to native timber production. On the contrary, by a cheapening policy he helps 
to depress it. 

5. Losses in planting from frost, drought, insects, fungi, and other cause.?. 

6. Confidence. — Low prices and lack of demand have shaken confidence in 
home timber production as an investment. To ensure planting by estates it 
is essential that this confidence should be restored. 

There are many other handicaps due to the general neglect and want of 
intei'est in forestry. 

Organisation . 

In developing or reconstructing an industry everything is dependent on 
organisation. 

We must have organisation of existing timber supplies, and organisation of 
future timber production. We must have also organisation of knowledge to 
prevent losses and ensure proper application of Practice with Science. 



72 REPORTS ON THE STATE OF SCIENCE, — 1918. 

II. Practice with Science. 

' Practice with Science ' has been always the motto of the Royal Agricultural 
Society. Forestry touches science at many points, and in the large developments 
of the near future science must play a leading part. I hope it will always 
be the policy also of the Royal English Arboricultural Society. 

In the past a great gulf has existed between science and practice, but by 
organisation this gulf should be bridged. 

The scientific man has worked at his jjroblem in his own world, and his 
researches and experiments were often unknown outside it. The practical 
man has gone on groping in the dark, observing things that happen, but 
reasoning badly as to cause and effect. What we wish to see is the removal 
of bamers and the advance of science and practice hand in hand, and the 
two branches brought closer together. 

7'he Journal of Forestry offei\s a good medium for the interchange of 
knowledge and for the co-operation of scientific and practical men with regard 
to forestry. 

Let us consider the directions in which they can work to mutual advantage, 
and particularly in solving the urgent problems likely to arise in the immediate 
future. 

In view of the large areas to be planted and the great quantities of seedlings 
which will be required, the first important problem in which science can assist 
forestry will relate to tree seeds and the raising and protection of the seedlings. 

Tree Seeds. 

The large planting developments pending will be carried out not only in 
this country but also on the Continent to replace forests and woods felled 
or destroyed in the war. In the past we have relied too much on Continental 
seed. Although in some directions it may be advantageous to use seed collected 
irom the country of origin, we must organise now a proper collection of native 
seed. The felling of so large a proportion of seed-bearing trees in this country 
makes the matter urgent. 

State grants are required to institute seed-testing stations and proper 
facilities in other necessary directions. 

Since the quality of the seed is a prime factor for successful planting, with 
each variety of tree we must decide on the best fy2}C, ogc, character, and situation 
of the parent-ti-ee from which the seed is collected. Geographical position 
and altitude are of less importance with native than with imported seed. 

Forester's differ as to the best age of the parent-tree, although the completion 
of height-growth is assumed generally to be the best age. 

Take Scots Pine as an illustration. 

The late Mr. Grant Thompson, who had a long experience, estimated the 
best age of the parent-tree to be sixty to seventy years. Seed from old trees 
is unsatisfactory and the cones ai'e then very small. If, however, the size 
of corre and vigour of seedlings are the principal guides, considerably younger 
parent-trees ar'e apparently practicable. Isolated trees growing on commons 
frequently bear very large cones at fifteen to twenty years of age, and fully 
developed seed which produces vigorous seedlings. One hesitates to suggest 
collecting seed from Scots Pine trees quite so yoxrng, but there is no doubt 
in my mind that the parents had better' be too young than too old. 

With Larch — and in this case we may have to rely more on native seed 
in the future — it is generally considered that seeds from the cones of larch 
of pitwood size will be unsatisfactory. Yet some practical foresters say they 
have obtained good I'esults from such cones. 

Take also the different types of the same forest tree, which types, in some 
cases, for good or ill, may be transmitted to the offspring. The oak is an 
example in which very careful selection of the seed appeal's necessary, and 
we have all noticed the extreme differences of type in the Corsican Pine. One 
type of Corsican in a parcel will have the characters of the coarser Austrian 
type, whereas another may be of a fine and erect description. 

In some directions it may be quite sound to select seed from what appear 
at the first glance to be unsatisfactory or coarse trees. Seed from hedgerow 



CORRESPONDING SOCIETIES. 73 

asli may possibly be more satisfactory than that from fine ash trees growing 
in high forest. The seed of the former has better means of ripening and 
other advantages, and in this case the rough tree is not due to unsatisfactory 
seed but to incorrect methods of production. The same argument may apply 
to Scots Pine grown on open commons. 

The average yieUh of conifer seed per bushel of cones is a point on whicli 
little information exists, and tests should be made and results compared and 
tabulated. 

The storing and extraction of the seed and other points which I cannot 
now touch upon afford also matter for diecussion. 

Nursery Work. 

Successful germination of the seed after sowing is of the first importance. 

The most important factor is moisture and, of course, warmth. It is usual 
to soak the seed to encourage early germination in the seed-beds. I think 
far greater attention should be given to this point, particularly with the seed 
of Douglas Fir and others that give uncertain results. The germination is left 
often too much to chance and to the risks of the weather, and I am convinced 
that far more even and certain germination can be obtained as a result of 
experiment and mutual di.scussion. 

Broadcast v. Drill Sowing. 

Both broadcast and drill sowing have their advocates, and it depends to 
a certain extent on the conditions which should be adopted. 
The advantages of broadcast sowing comprise chiefly : 

(1) Less land is required for the seed-bed*. 

(2) Less laboui' is required for sowing and a given quantity of seed 
is sown more quickly. 

(3) Once a vigorous crop of seedlings Ivas sprung up, the weeds are 
suppressed naturally and in the later stages less attention is required. 

(4) Lees expense is involved in shading and other operations. 

One of the disadvantages of broadcast sowing is suppressing the weeds in 
the early stages. 

The advantages claimed for drill sowing are that the seeds can be hoed 
between the lines and that the seedlings are properly mulched and less crowded. 

Broadcast sowing is far more general now than drill sowing, both here and in 
America. 

Thichiess of Sowing. 

The number of square feet covered per pound of seed is a point to which 
attention should be given. Many experienced men prescribe eighty to a 
himdred square feet to the pound of seed for the broadcast sowing of most 
conifers. All agree, however, that Sitka Spruce requires double or treble the 
area per pound of seed. 

The area should be based, of course, on the number of seeds to the pound 
and the percentage of germination. There are also special characteristics 
attaching to each variety of tree, and I think that a revised table on this 
point is required. 

Shading, dc. 

Protection from sun and frosts is an important question in the early stages 
of seedling production. Various devices are used for protective purposes, 
including wire netting, rods of bamboo, Ixjughs, &c. Birch boughs are an 
inexpensive resource for this purpose, and all agree as to the wisdom of not 
using the boughs of conifers. 

Shading the seed-beds with cheese-cloths or coarse canvas is comiuon in 
America and might be adopted in this country with certain varieties such as 
Sitkfi Spruce. 



74 REPORTS ON THE STATE OF SCIENCE.— 1918. 

The important point is to prevent ' damping off ' or the encroachments of 
fungi, while allowing proper light and air to get to the seedlings and protecting 
them in their early stages from extremes of temperature. 

The fungi and other pests attacking the seedlings, and also the trees after 
planting, and steps to combat them, also the question of manures and their 
application to forestry operations, afford many points in which we need and hope 
for' the assistance of science. 

Woman Labour. 

Attention might be called to the great possibilities offered to female labour 
in the work of seedling production. Women have great aptitude for gardening, 
and there are probably few directions where they can be more usefully employed 
in the near future than in supervising the various operations connected with 
nursery work. I hope that full facilities for training them will be instituted 
and proper opportunities afforded them for extending their usefulness in this 
direction. 

Afjorestation. 

It is seldom appreciated how gravely forestry and planting have been 
depressed during the past generation by losses and mishaps in establishing 
the crop. 

Great opportunities lie open to science for assisting forestry to prevent or 
minimise losses from frost, drought, insects, fire, gales, and particularly fungi. 
I would remind you that in this country the extension of forestry as an 
iiidustiy is in its infancy, and in many directions offei's ahnost a virgin field 
for scientific investigation. The problem is urgent for replanting the felled 
areas at the earliest moment, before the vigorous growth of grass and under- 
growth entail far greater expense in establishing the crop. Science already has 
pointed to a possible method of keeping down bracken by spraying with a 
v/eak solution of sulphuric acid. The burning over of the areas to produce 
potash for the benefit of the young trees is worthy of extended investigation, as 
can be judged by observation of results secured where burning has been done 
effectively. 

Transplanting. 

When planiting out, the proportion of losses varies greatly with each 
description of tree. Corsican Pine is admittedly one of the most difficult, 
although intelligent and careful nursery treatment reduces the losses materially. 
Transplanting every year from the one-year seedling is a good method to adopt, 
but usually somewhat expensive. 

A treatment I have found successful with Corsican Pine consists in taking 
the one-year seedlings from the seed-beds (but not separaiting them) late in 
April and transplanting them thickly but upright in lines. The following 
season the seedlings can be transplanted into lines, say fifteen to the 
yard. In addition to being transplanted yearly, they should be ' slacked ' 
also at least once during the summei'. Slacking consists in lifting them with 
a fork, and treading them in again without taking them out of the ground. 
Slacking is important also to check the growth of Douglas Fir, but damp weather 
should be chosen for the operation. 

I fear practical foresters often confuse cause and effect, and I will give 
an illustration. Yew and holly are probably two of the most uncertain trees 
to transplant. The foliage in both cases usually dies back after transplanting. 
Many gardener's and foresters will tell you as a guide to results that if the 
leaves fall off the tree will live, but if the withered foliage is retained the 
tree will die. Professor J. B. Fanner, however, informs me that the retention 
of the withered or dead leaves is probably the cause of death, and that if these 
are removed few of the trees will die. 

I have always advocated as a result of observation that it is best to cut 
Thuya plicata down to ground level after transplanting from the seed-bed. 



CORRESPONDING SOCIETIES. 75 

I mention these facts also to indicate the advisability under certain 
circumstances of removing the lower branches of Douglas Fir when planting 
out. From comparing results I am sure this reduces losses, and it also prevents 
the seedlings from being blown over by gales. I would remind you that the 
Douglas Fir is the safest of all trees to prune. 

Time will not allow of detailed reference to losses from frost, drought, fire, 
and gales, but I hope these matters will have full attention from scientists 
in the future. 

Real and effective help may be given to forestry by this means. 

Conclusion. 

Forestry is entitled to every encouragement. Enough has been said as to 
State encouragement, which should be at least threefold : 

1st. The iiemoval of handicaps. 

2nd. The prevention of losses. 

3rd. The ensuring of a proper return from planting. 

Of equal importance is the encouragement of forestry by the individual, 
including the townsman and even the school children of the rising generation. 
There is always one effective method of encouraging any industry or pursuit, 
and that is cr'eating interest and disseminating knowledge. 

A national Arbor Day is suggested— a movement veiy popular and effective 
in America. Anything that will encourage forestry should be assisted, but 
whatever steps are taken should be on sound and properly organised lines. 
It must not lead to haphazard planting and bad results. The most important 
branch of forestry in the future must be sj/lriculture, and this should be borne 
in mind in encouraging Arbor' Day, or planting of trees in general. Arbori- 
culture and town planting on garden city lines deserves every encouragement, 
but this must not prejudice proper methods of sylviculture, or the cutting down 
of timber on proper rotation in State forests. 

I mention this only as a timely warning, but I hope that an Arbor Day may 
be instituted and even war memorials take the shape of planting trees. 1 
think that I can vouch for the co-operation of the Forestry Societies in 
establishing Arbor Day and secure the assistance of experienced foresters to 
supervise the actual planting. 

W/iat is necessary to put all these forestry matters on a proper footing? 
Proper snfrport of the Forestry Societies, real encouragement by the State 
and by those in authority, and effective interest by industrial concerns, urban 
voters, and the British public. 

Mr. J. HoPKiNSON (Hertfordshire Natural History Society) reminded the 
Conference that last year, after his address as President, he suggested that 
an Arbor Day should be instituted. He considered Afforestation to be one 
of the most important questions that could be brought before them. We were 
rapidly exhausting our forests ; for several years we had been cutting down 
oiu" trees at an enormous rate. His object in suggesting that this subject 
should be brought before them again was, that they ehould pass a resolution 
in the Conference fixing a day, and pledging themselves, and the members 
of their societies, as far as they possibly could, each to plant at least one 
tiee on that day. He hoped they would communicate this to their societies, 
and get them to pass a resolution to the same effect. He suggeste<l the month 
of October as about the best to plant trees, and we had in that month a very 
memorable day : the 21&t of October (Trafalgar Day). He was of opinion 
that for the whole of the United Kingdom, Great Britain and Ireland, we could 
not bave a better one. He would go further, and suggest that each of them 
in their respective locality should communicate with their Parliamentary repre- 
sentative, urging not only that the .'^tate sliould accept it, but that it should 
be made a National Holiday. 

He believed it could be "done by very strong pressure. Possibly they might 
not keep to October 21 ; but they sh^oiild keep as close to it as possible. He 
would move 'That the members" of this Conference pledge themselves to the 



76 KEPORTS ON THE STATE OP SCIENCE. — 1918. 

best of their ability to plant one tree at least on an established day and to 
endeavour to get as many other members of their Society as they can to do 
the same.' 

Sir Charles Bathurst (now Lord Bledisloe) was very glad to second the 
resolution, which he was sure ought to commend itself to every patriot who 
realised the position in which we had found ourselves in relation to timber 
during the war, and the extreme difficulty of repairing within a reasonable 
time the wastage which the war has occasioned. He hoped that the resolution 
would not be taken only to refer to those who had large properties or who 
were carrying on scientific operations — he ventured to hope that it would be 
made to apply to everyone who owned land of an agi'icultural character 
throughout the country, so that this patriotic obligation would rest upon and, 
he hoped, affect the conscience of, everyone interested in agricultural land. 
We owed gi-eat thanks to jNIr. Duchesne for the way in which he had for' years 
past pushed the claims of Forestry. The nation wa« under a real debt to 
him for the work which he had so patriotically undertaken. All his prophecies 
before tlie war — and he (Sir Charles) had listened to a good many of them — 
with r'egard to the subject had been more than fulfilled. But an apathetic public 
disregarded his warning. Perhaps I\Ir. Duchesne and he had that much in 
common, because he had uttered similar jeremiads to deaf ears as to the 
effect on the country of shoi'tsighted neglect in the matter of the home 
production of essential foods. As far as anyone could at present foresee, after 
the war shipping tonnage would be scarce for several j^ears. Unfortunately 
home-grown timber would be scarcer than ever, although we should be all the 
more dependent upon home-grown supplies. The gentleman who had just 
spoken had very properly said that we must increase them. He said that 
landowners would not plant ti'ees. No ; a certain sort would not, and he 
for his part, as one of them, did not blame them. It was very difficult to 
induce them to provide any commodities out of which there was not a fair 
chance of making a reasonable profit. He did not r'egard timber as having 
been in the past such a commodity. We must alter all that, or the country 
would not get timber any more than it could get food without reasonable 
encouragement and inducement. AVe must look to the Government, not only to 
show us how to do it by cari-ying on timber production commercially on a 
lai'ge scale itself, but also to help those who were prepared to co-operat-e with 
it in this national task. He lived on the border of the Forest of Dean : 
and the past experience there of commercial timber production on the part of 
the Government was not such as to carry great conviction to the individual 
landowner who was prepaiied to do his part in his own generation. In the 
further course of his remarks, Sir Chai-les said that there was a great scarcity 
of timber seed, and asked what was the Government doing to provide this 
timber seed, to enable landowners to carry out the task that they were asked 
by the Government to carry out for the next ten or twenty years? They were 
cutting down in the summer' trees which in the autumn might yield some of 
these seeds. Sir Charles cojicluded with the observation, that he always listened 
to Mr. Duchesne with increasing interest and increasing conviction, and he 
looked forward to the time when all landowners, and perhaps the general 
public also, would realise the enovnious importance of the gospel which Mr. 
Duchesne so effectively preached. 

Mr. A. W. Oke (Brighton and Hove Natural History and Philosophical 
Society) suggested that the names of John Evelyn and William Cobbett should 
be associated with the subject, and after remarking that everything was going 
to be done after the war, asked what was going to happen in the case of 
the insect pests, with the fungi and the other things that were spoiling the trees 
as they existed now. He did hope that something would be done at once. 

Mr. William Dale (Hampshire Field Club and Archajological Society) asked 
Mr. Duchesne why he had got his knife into the bracken. It made an excellent 
and exceedingly warm litter ; he had also heard that the tops made excellent 
food ; but he had not had the courage to try them. 

The President remarked that he had. They were not nice, but they were 
good. 



CORRESPONDING SOCIETIES. 77 

Mr. Whitaker thought it a capital thing that they should have heard an 
expert on his own particular subject. For himself, he was met with certain 
difliculties. It seemed to him th.at some folk wanted to niake our country a 
pui-ely agricultural one. They must allow us other industries. We had got 
to recollect one thing. England is a very small land and it became a question 
whether such an insignificant bit could supply all its own needs. If timber 
is wanted — and it is now — he very much doubted whether we could produce 
all we wanted. We ought to increase our products ; but in the case of some 
of our timber supplies we cannot, because they do not grow in this country. 
He agr'eed with the speaker heartily that care should be taken to treat our 
trees properly. With reference to an Arbor Day, if he had to plant a tree it 
must be in his garden. He did not want a tree in his garden; he should cut 
one down if it were there, unless it were an apple-tree or something of that 
sort. He thought we should increase our supply of fruit in this country. This 
Ai'bor Day seemed to him a little bit of a festival as much as anything else, and 
he did not see why we should have any more Bank Holidays. Undoubtedly 
Government should in many instances give a lead, but that Government should 
take over everything, or heavily subsidise everything, seemed a mistake. He 
hoped people would be a little more careful about how they called upon us 
to tiike up one particular thing and about calling in the Govermuent to help. 

The President sympathised with Mr. Whitaker's remarks very strongly. 
Had planting a tree anything to do with the good of the country except 
sentimentally ? The difficulty really came in our suburbs and towns. We had 
got a large population in our suburbs. Where were we to plant ? That was 
the big difficulty he had been trying to solve for a long time. What we wanted 
to do was far more to bring pressure to bear upon people to do something 
practical in the way of High Foi'est cultivation. Alluding to the devastation 
of which Mr. Hopkinson had spoken, and to there being no provision as tar as 
he could see for replanting, the President said that, if there was not good 
reason for it in such cases as this, they might bring such influence as their 
Societies had to bear, they could get all their members to write to their members 
of Parliament and make themselves generally unpleasant on the matter. He 
took it that in Mr. Duchesne's opinion the preservation and collection of seeds 
was a task on which they might be engaged. If he could give them some 
practical instructions or suggestions that they might bring before the members 
of their societies, he would be glad. Insect pests and fungi had been mentioned. 
Perhaps if some of their members turned more detailed attention to those 
practical points, they would be doing a service. 

Mr. Bevan observed that Arbor Day was a practical thing in the United 
States, and pointed out that it enabled teachers to .get the children to help 
in it and to be receiving instruction by means of it. He thought Mr. Duchesne 
would have added to the value of his paper if he had included the subject 
of wood-pulp. As to Government assistance, one should differentiate. He 
thought this particular matter was a subject on which the Government must 
come in. If one did not get a reasonable return for foi*t.y or fifty years, it 
was absolutely necessary. There could be no reasonable objection to the 
Government making a reasonable bargain by lending a certain amount of money 
on reasonable interest. On the subject of wood-pulp he said that Canada not 
only exports to the Mother Country a considerable amount of timber and wood- 
pulp, but to the United States. He was told that the timber from one acre 
of ground every day was made into wood-pulp for the use of one of the New 
York papers. There was no cjuestion about it that this was one of the most 
important subjects, and that the Government had been criminally negligent up 
to the present time. 

The Secretary (the Selborne Society) supported Mr. Hopkinson. Because 
there were one or two difficulties mentioned by ]\[r. Whitaker, he did not see 
that that was any reason why we should not have an Arbor Day in this country. 
It would be a very complimentary thing to the United States on Independence 
Day to do their best to start an Arbor Day. It would ^ive them an opportunity 
also to send a message of a practical character. If Mr. Whitaker wanted an 
apple-tree, let him plant an apple-tree on Arbor Day. The resolution only 
pledged them to the best of their ability. Perhaps the best thing would be to 
1918. Q 



78 REPORTS ON THE STATE OF SCIENCE. — 1918. 

do it collectively, and ask a landowner in the neighbourhood to plant an acre. 
That would be increasing eylvicultui'e, and it would be a sort of advertisement 
of High Foresti-j'. He should like to support the motion even if it were to 
be modified in the canying out. 

The President, before Sir Charles Bathurst left, expressed the thanks of 
the Conference to him for leaving his ' sweet ' duties in order to give them 
an address. 

Sir Charles Bathuhst said that it was a real pleasure to him and a real 
recreation from his ' sweetmeats. ' 

Mr. Mark Sykes (^Manchester Microscopical Society), speaking on Arbor 
Day, said he did not think it was practical as proposed. Where were they 
going to get the land, and from whom were they going to get the permission 
to plant a tree ? He did not see how that Conference could pledge its societies 
or the societies their members. What was wanted was, that the subject should 
be taken up by the landowners and by the Government ; by all the people 
who had lar'ge tracts of land. There should be a systematic laying out of large 
plots, and a proper system of planting trees suitable to the ground in which 
they were planted : trees both of commercial and food value. This should be 
done chiefly by the landed proprietors. They came into properties ; it cost 
nothing to plant trees ; the seeds were there in thousands and millions. Land 
which has borne a forest is land best suited to bear another. There was nothing 
better than leaves from the trees for the ground ; and the ground was already 
pr'epared for a future forest. 

Mr. HoPKiNsox thought one objection was already met by his reservation 
'to the best of their ability.' 

Mr. Duchesne, who felt very much flattered by the length and interest of 
the discussion, could not agree with Mr. Sykes that there was no cost in planting 
trees ; they found it veiy costly. From his experience of the forests of Canada, 
also, he could assure them that it was not correct that new forests sprang up 
from the old forests. He had been all over the Continent, and in every country 
their firist aim was to get natural pi'oduction from the seeds. Unfortunately 
grass and weeds grew up so fast that they smothered the seedlings. Therefore 
they had to raise trees in the nursery and plant them out. 

He vas particularly interested in wood-pulp, but there were so many points 
to deal with, and he had dealt with wood-pulp in a paper read in the early 
part of the year. Spruce (white deal) could be grown for wood-pulp. 

Eeplyin^ to Mr. Wliitaker, who had protested against being urged to do one 
thing from one quai-ter and another from another, and as if each thing should 
be our sole business in life, Mr. Duchesne said that their suggestions as to 
afforestation did not conflict with any of those for food production, whether 
it were cereals or fruit. What they suggested was not that the whole of our 
eupply should be grown : it was quite impossible. Obviously, we could not 
grow mahogany, though there is no other country in the world that can produce 
so many varieties successfully. But we must create reserves, so that in an 
emergency we could draw on them as an insurance. The Prime Minister had 
spoken of the immense quantity of tonnage taken up in the transport of timber 
to this country. 

As to Arboi' Day, he was in favour of anything that would encourage 
interest and educate the people in .the country — the children particularly. He 
supported Arbor Day because he thought it would do a great deal to encourage 
forestry. 

His great wish was that those men sent from the lumber camps in Canada 
to fell the timber in this country and France, should go back to their own 
counti-y and take an interest in forestry as well as in lumber. 

As to agriculture, he had been connected with it all his life, and was as 
keen as anyone on it, and he quite agreed with Mr. Whitaker as to the 
extension of fruit industries in this country, particularly in the growing of 
apples and such fniit with discretion. 

One speaker had referred t/o John Evelyn and William Cobbett. He had 
for a text in his last paper an extract from John Evelyn's book, which was 



I 



CORRESPONDING SOCIETIES. 



79 



of course a classic of Forest Literature — an extract from Evelyn's ' Sylva,' 
written in 1664 : 

'It will appear that we had better be without gold than without timber.' 

He wante<l bracken destroyed on the areas to be planted, because it came 
up so thickly that it suppressed their little trees after they had planted them 
— larcli trees, for instance. 

Mr. Duchesne dwelt upon the urgent importance of the collection of eeeds. 
He hoped in the coming season to make a larger appeal for the collection of 
tree seeds, and he would communicate with Air. Webb and the President, 
and if the societies in every direction would help them in collecting, full 
insti'uctions and every a.^sistance would be given in that collection. 

The President said, if they could have a supply of the instructions sent, 
they would be delighted to send them to their societies. 

The following resolution was now carried nem. con. 

' That the Delegates present at this Conference pledge themselves 
to the best of their ability to plant a tree on Arbor Day and to 
induce all the members of their societies to do the same ; and that 
the suggested day be October 21.' 

The Secretary then I'ead a note on an exhibit of a Tvpomap made by 
Mr. B. B. Woodward, F.L.S., F.G.S. 

The accompanying Typomap was prepared in connection with the Committee 
of the British Association appointed ' to formulate a definite system on which 
collectors should record their captures.' This committee appears to have lapsed 
without completing its mission. 

The object of the map is to enable observers to record occurrences with 
sufficient approximate geographical accuracy without incurring the expense 
of specially engraved maps. 

When working out the distribution of a given species the observer can 
take one oi these map.s and mark those areas in which it occurs in any way 
that may best suit him. If used in illustrating a printed paper, occurrences 
can be shown by using lieavier type, or printing the area in question in red 
as done in the ' Catalogue of the British Species of Pisidium,' published by 
the Taistees of the British Museum. 

It may be of interest to point out that the first typomap designed was 
that for Finland utilised in the ' Herbarium Musei Fennici . . . editio secunda. 
I. Plantoe Vasculares,' 8vo., Helsingfors, 1889, published by the ' Societas pro 
Fauna et Flora Fennica.' 

Being the first of its kind it seems of sufficient interest to be repi'oduced 
here. 



Lc 



Li Lt Lmur !_ 

Likem Im Lv Lp 

Ob Ks Kk 

Om Ok Kp 

Oa Jb Sb Kb On 

St Ja Sa Ivl 01 



Al Ab N Ka Ik 



The principle appears to have been next applied by R. Lloyd Praeger to the 
case of Ireland {Irish Naturalist, xv. 1906, pp. 6*8-94) with great success. His 
further attempt in the same article to extend the treatment to the 
whole of the British Islands was, however, not quite so successful, and 
the present version was undertaken by myself with the view of obtaining a 
better total result, the arrangement for Ireland being left undisturbed. 

ci2 



80 



REPORTS ON THE STATE OF SCIENCE. — 1918. 



HB 



TYPOMAP OF THE BRITISH ISLES. 



SI 
Oi 

NS CA 

SS 

RW RE EL BF AN 

Wl El PN AS 

AM PM FF Kl 

DN SG PC KF 
B 

RF LL ED HD 

AY LA PE BW NN 

WT KB DF SK RX SN 



M 



CT 



WD ED LD AN 

FE TY AR DO 
WM SL LE MO 

EM RO CV LH 
WG NG LF WH ME 
SG KG KD DU 
CL NT QC CW Wl 
NK LK ST KK WX 
SK MC EC WA 
WC 



IM 



CU WL NY DM 

ML MY EY 

SL WY SY LN 
A 

OR DB FT CH DY NM LS 

MN MG SP ST LR CB WN EN 

CD RA HF WO WW NO HU WS ES 

PB CM BR GE OX BX BD HT NE 

GM MM GW NW BK MX SE 

H 

NS SW NH SR WK EK 
L 

ND SS DT SH WX EX 



EC SD 



IW 



SC WC 



CI 



COKRESPONDING SOCIETIES. 



81 



KEY TO THE SYMBOLS FORMING THE MAP. 



A = Anglesey. 

AM = Argyll, Maiu. 

AN (Scot.) = Aberdeen, Nortli. 

AN (Ire.) = Antrim. 

AR = Armagh. 

AS = Aberdeen, South. 

AY = Ayr. 

B = Bute, Arrau and Clyde 

Is. 

80 = Beds. 

8F = Banff. 

BK = Berks. 

BR = Brecon. 

BW = Berwick. 

BX = Bucks. 



CA 

CB 

CD 

CH 

CI 

CL 

CM 

CR 

CT 

CU 

CV 

CW 



= Caithness. 
= Cambridge. 
= Cardigan. 
— Cheshire. 
= Channel Is. 
= Clare. 
= Carmarthen. 
= Carnarvon. 
= Cantire. 
= Cumberland. 
= Cavan. 
= Carlow. 



OB = Denbigh. 

OF = Dumfries. 

OM = Durham. 

ON = Dumbarton. 

DO = Down. 

OT = Dorset. 

DU = Dublin. 

OY = Derby. 

EC (Eng.) = East Cornwall. 

EC (Ire.) = East Cork. 

EO (Scot.) = Edinburgh. 

EO (Ire.) = East Donegal. 

El = East Inverness. 

EL = Elgin. 

EK = East Kent. 

EM = East Mayo. 

EN = East Norfolk. 

ES = East Suffolk. 

EX = East Sussex. 

EY = North-east Yorks. 

FE = Fermanagh. 
FF = Forfar. 
FT = Flint. 

GE = Gloucester, East. 
GM = Glamorgan. 
GW = Gloucester, West. 

HB = Hebrides. 



HO = Haddington. 

HF = Hereford. 

HT = Herts. 

HU = Hunts. 

I = Islay, etc. (Ebudes S.). 
IM = I. of Man. 
IW = I. of Wight. 

KB = Kirkcudbright. 

KC = King's County. 

KD =Kildare. 

KF = Kinross+Fife 

Kl = Kincardine, 

KK = KUkenny. 

X = London (Postal Dis- 
trict). 

L = Lundy I. 

LA = Lanark, 

LD = Londonderry. 

LE = Leitrim. 

LF = Longford. 

LH = Louth. 

LK = Limerick. 

LL = Linlithgow. 

LN = Lincoln, North. 

LR =» Leicester+Kutland. 

LS = Lincoln, South. 

M = Mull, etc. (Ebudes, 

Mid.). 
MC = Mid Cork. 
ME = Meath. 
MG = Montgomery. 
ML = Mid. (or West) Lanes. 
MM = Monmouth. 
MN = Merioneth. 
MO = Monaghan. 
MX = Middlesex. 
MY = Mid. West York;. 

NO = North Devou. 

NE = North Essex. 

NG = North Galway. 

NH = Noi-th Hants. 

NK = North Keny. 

NM = Notts. 

NN = North Northumberland. 

NO = Northants. 

NS (Eng.) = North Somerset. 

NS (Soot.) = Nortli (or East) 

Sutherland. 
NT = North Tipperary. 
NW = North Wilts. 
NY = North-west Yorks. 

Ol = Orkneys. 
OX = Oxford. 

PB = Pembroke. 



PC = Perth, South (or West) 

-h Clackmannan. 
PE = Peebles. 
PM = Perth, Mid. 
PN = „ North (or East). 

QC = Queen's County. 

RA = Radnoi-. 
RE = Ross, East. 
RF = Renfrew. 
RO = Roscommon. 
RW = Ross, West. 
rX = Roxburgh. 

S = I. of Skye, etc. (Ebudes 

North). 
SC = Scilly Is. 

50 = South Devon. 
SE = South Essex. 
SG (Scot.) = Stirling. 

SG (Ire.) = South Galway. 
SH = South Hants. 

51 = Shctlands. 
SK(Scot.) = Selkirk. 

SK (Ire.) = South Kerry. 

SL (Eng.) = South Lanes. 

SL (Ire.) = Sligo. 

SN = South Northumberland. 

SP == Salop. 

SR = Surrey. 

SS (Eng.) = South Somerset. 

SS (Scot ) = South (or West> 

Sutherland. 
ST (Eug.) = Stafford. 
ST (Ire.) = South Tipperary. 
SW = South Wilts. 
SY = South-east Yorks. 

TY = Tyrone. 

WA = Waterfonl. 

WC (Eng.) = West Cornwall. 

WC (Ire.) = West Cork. 

WD = West Donegal. 

WG = West (Jalway. 

WH = Westmeath. 

Wl (Scot.) = West Inverness. 

Wl (Ire.) = Wicklow, 

WK = West Kent. 

WL = Westmorland. 

WM = West Mayo. 

WN = West Norfolk. 

WO = Worcester. 

WS = West Suffolk. 

WT = WigtOM. 

WW = Warwick. 

WX (Eng.) = West Su^ex. 

WX (Ire.) = Wexford. 

WY = South-west Yorks. 



82 



REPORTS ON THE STATE OF SCIENCE. — 1918. 



LIST OF COUNTIES, WITH THEIR SYMBOLS. 



ENGLAND. 

Betls BD 

Berks BK 

Bucks BX 

Cambridge . . . . CB 

Cheshire CH 

Cornwall, East . . . . EC 

West .. .. WC 

Cumberland .. CU 

Derby DY 

Devon, North . . N D 

„ South .. .. SD 

Dorset DT 

Durham DM 

Essex, North .. NE 

„ South .. .. SE 

Gloucester, East . . .. GE 

West .. .. GW 

Hants, North .. .. NH 

„ South .. .. SH 

Hereford HF 

Herts HT 

Hunts ., .. .. HU 

Kent, East EK 

„ West .. WK 

Lancashire, Mid. (or W.).. ML 

„ South .. SL 

Leicester with Rutland . . L R 

Lincoln, North .. .. LN 

„ South .. .. LS 

London (Postal District) X 

Middlesex MX 

Monmouth MM 

Norfolk, West .. .. WN 
East .. ..EN 

Northants . . . . NO 

Northumberland, North . . NN 

„ South.. SN 

Nottingham .. .. NM 

Oxford OX 

Rutland. See Leicester. 

Salop SP 

Somerset, North . . .. NS 

„ South . . . . SS 

Stafford ST 

Suffolk, West .. .. WS 

„ East .. .. ES 

Surrey SR 

Sussex, East . . . . EX 

„ West .. .. WX 

Warwick WW 

Westmorland + Lanes., N. WL 

Wilts, North .. .. NW 

„ South .. .. SW 

Worcester WO 

Yorks, North-west . . NY 

,, -Mid- west.. .. MY 

„ Nortli-east .. EY 



Yorks, South-west 


WY 


Ross with Oromartv, East 


RF 


,, South-cast 


SY 


J, „ „ West 


RW 






Roxburgh . . 


RX 


Clmuuclls. 


CI 


Selkirk 


Si< 


[.of Man 


IM 


Shetlanda 


SI 


I. of Wight 


IW 


Stirling 


SG 


Lundy I 


L 


Sutherland, North (or E.) 


NS 






South (or W.) 


SS 


WALES. 




Wigton 


WT 


Anglesey 


A 






Brecon 


BR 


Hebriiles 


HB 


Cardigan 


CD 


Skye, &c. (Ebudes, N.) . . 


S 


Carmarthen 


CM 


Mull, &c. (Ebudes, Mid.) 


M 


Carnarvon 


CR 


Islay, &c. (Ebudes, S.) .. 


1 


Denbigh 


DB 


Bute and Clyde Is. 


B 


Flint 


FT 






Glamorgan 


GM 






Merioneth 


MN 


IRELAND. 




Montgomery 


MG 


Antrim 


AN 


Pembroke] 


PB 


Armagh 


AR 


Radnor 


RA 


Carlow 


CW 






Cavan 


CV 


SCOTLAND. 




Clare 


CL 


.Aberdeen, North . . 


AN 


Cork, East 


EC 


„ South 


AS 


„ Mid 


MC 


Argvle, Main 


AM 


„ West 


WC 


Ayr .. : 


AY 


Donegal, East 


ED 


Banff 


BF 


„ West .. 


WD 


Berwick 


BW 


Down 


DO 


Caithness 


CA 


Dul)lin 


DU 


Cantire 


CT 


Fermanagh 


FE 


Clackmannan. Sep Perth, 




(lahvay. West .. 


WG 


South. 




North .. 


NG 


Cromarty. See Ross. 




„ South .. 


SG 


Dumbarton 


DN 


Kerry, North 


NK 


Dumfries . . 


DF 


South 


SK 


Edinburgh 


ED 


Kildare 


KD 


Elgin 


EL 


Kilkenny 


KK 


Fife. See Kinross. 




King's Co. 


KC 


Forfar 


FF 


Leitrim 


LE 


Haddington 


HO 


Limerick 


LK 


Inverness, E 


El 


Londonderry 


LD 


W 


Wl 


Longford 


LF 


Kincardine 


Kl 


Lonth 


LH 


Kinross-hFife 


KF 


Mayo, East 


EM 


Kircudbright 


KB 


„ West 


WM 


Lanark 


LA 


Meath 


ME 


Linlithgow 


LL 


Monaghan 


MO 


Nairn. See East Inver- 




Queen's Co. 


QC 


ness. 




Roscommon 


RO 


Orkneys 


Ol 


Sligo 


SL 


Peebles 


PE 


Tipperary, North 


NT 


Perth, North (or East) . . 


PN 


„ South 


ST 


., Mid 


PM 


Tyrone 


TY 


„ South (or West), 




Waterford 


WA 


with Clackman- 




Westmeath 


WH 


nan 


PC 


Wexford 


WX 


Renfrew 


RF 


Wicklov/ 


Wl 



CORRESPONDING SOCIETIES. 



83 



SUBDIVISIONS OF COUNTIES. 



ENGLAND. 

CORNWALL, East and West: are separated 
by the high-road from Truro, through 
St. Colunnb to the inland extremity of 
Padstow Creek. 

DEVON, iVor^/t fu«i South: are divided by 
a line beginning at the Tamar, about 
midway between Tavistock and Launces- 
ton, passing over the ridge of Dartmoor, 
and joining the western canal at Tiverton. 

^S8'E\, North ami South: are divided by 
the high-road from Waltham and Epping 
to Chelmsford, and thence by the Rivers 
Chelmer and Blackwater to the coast. 

GLOUCESTER, East and West: are sepa- 
rated by the Thames and Severn Canal 
and the River Severn to Tewl;esbury. 

HANTS, Noi'th and South : are separated by 
the high-roads from Winchester westward 
to Stockbridge, eastward to Petersfield, 
and continued thence to the borders of 
Wilts and Sussex. 

KENT, East and West: are sepai'ated by 
the River Medway nearly up to Staple- 
hurst, and thence by the high-road through 
Cranbrooke to the border of Sussex. 

LANCASHIRE, M*fL(TFes< of Watson) and 
South : are divided by tlie River Ribble. 
Lancashire to the north-west of More- 
cambe Bay is united with Westmorland. 

LINCOLN, North and South : are separated 
by the River Witham fi'om Boston to 
Lincoln, thence by the Foss Dyhe to the 
border of Nottinghamshire. 

NORFOLK, East and West : are divided by 
the hne 1° E. leng. 

NORTHUMBERLAND, North and South : 
are divided by the River Coquet and a line 
from the Linn Bridge to Carter Pell. 

SOMERSET, iVor«7t and South: are sepa- 
rated by the River Pairet, from Bridge- 
water to Hchester, and thence roujid to 
the northern extremity of Dorset. 

SUFFOLK, East and West : are divided by 
the hne 1° E. long. 

SUSSEX, East and West : are divided by 
a line along the high-road from Brighton 
to Cuckfield, thence by Crawley to the 
borders of Surrey. 

WILTS, North and South : are divided by 
the Kennet and Avon Canal. 

YORK, first divided into East and West 
Huniber, by the Rivers Humbei-, Ouse, 
Swale, and Wiske. 

S E. and N E. Yorks are then separated 
by the East Riding boundary. 



S.W. and Mid.-W. Yorhs by the Leeds 
and Liverpool Canal, and the River Aix-e 
below Leeds; and 

Mid.-W. and N.W. Yorks by the boun- 
dary between the N. and W. Ridings. 

SCOTLAND. 

ABERDEEN, North and South : are sepa- 
rated by the watersheds eastward and 
westward of Inverury. 

A'RGYL'E, Main, and Cantire ■, are divided 
by the Crinan Canal. 

INVERNESS, East and West : are separated 
by the watershed between east and west 
Scotland, continued along L. Erricht to 
the borders of Perthshire. Naii n is in- 
cluded in E. Inverness. 

PERTH, North (£<(.?< of Watson) and Mid.: 
are divided by the Rivers Garry and Tay. 

Mid. and South {West of Watson) : by 
the watershed between the Rivers Tay 
and Forth. 



are divided by the 
the east and west 



ROSS, East and West 
watershed between 

coasts. 

SUTHERLAND, North {East of Watson) 
and South {Wfst of Watson): are sepa- 
rated by the watershed. 

IRELAND. 

CORK, East and Mid.: are divided by the 
railway line from Charleville to Cork, and 
west shore of Cork Harbour. 

Mid. and West: by the Killarney Railway 
from the Kerry border to Blillstreet, 
thence in straight lines to Macroom and 
Bandon and the Bandou River. 

DONEGAL, East and West : are divided 
by a line separating the baronies of 
Bannagh, Boylagh, and Kilmacrennan 
from those of Tirhugh, Raphoe, and 
Innishowen. 

GALWAY, North and West: are divided by 
L. Corrib. 

North and South : by the railway from 
Oranmore to Ballinasloe. 

KERRY, North and, South: are divided 
by the line separating tlje baronies of 
Magunihy and Trughanacniy from those 
of Glanarought, Dunkerron, Iveragh, and 
Corkaguiny. 

MAYO, East and West : are divided by 
the railway from Ballina to the head of 
L. Mask. 



TIPPBBARY, Norlh and South: 
divided by the lino of the watershed. 



are 



84 REPORTS ON THE STATE OF SCIENCE. — ^1918. 

The Secretary next gave a summary in the author's absence of a paper 
by Mr. Percival Westell on 'Grants to Regional Museums.' 

The President did not think they could do more than express their thanks 
for the paper, and to say that they did not see their way to do anything 
further in the matter. If anyone should take up the case it should be the 
Museums Association. 

It was agreed to send a copy of the Arbor Day resolution, signed by the 
President and Secretaiy, to the United States INIinister of Agriculture. 

In conclusion the Conference expressed its thanks to its President, and to 
the Geological Society for its kindness in lending the meeting room. 



CORRESPONDING SOCIETIES. 



80 



at 

05 



I 

00 



Oi 



as 
o 

X 

o 

? 

-< 

o 

o 

on 



& -2 
pq '8 

o 
£ '« 
o ;:^ 

E ^ 

» 

o 

cc 

o 

Q 
iz; 
O 
0. 
m 

O 

O 




00 

^ 00 <•'« us ^bj 

l-H « ^ O -H 



oj o 00 o 



ss 

OS V 



1^ 



C K a 

1 1 
g P3 li. 



03 



a 
o 
<»^ 



a 
a 

S 
Q 



3 i 

"2 a S 
S "i 



i '^ o 



g M 
O CO 

tri bo 

o a 






I ^ 



= PU 



-- - © 



2 o 

3 2 

^ txcc 

* a m 
&0.2 






5 % S3 



a g 



- 2 2 = « 2 °' 

■ S M -^ -^ k^' J ^ 

P3 W <1 P3W 



fe a 

^ a 

^ a 

CQ S 

<c s 
■So 

03 r 

a " 

CO *^ 

o! a) S 
0) J3 j; 

>" o . 

^1^" 



H 






3 



a 

Hi 

c o 



O 03 



Sob 



C5 s 



— -a 

3 
PM 



S&.J 



CO 



Q ^ r~ O O 

, ~ o' " • 

< A n 



a 




u 





!H 







-a 


0) 








s 



o o 



11 if 



a oj 

y 

>> . 

•Id 



■— 3 



.9^ 

M ^ OJ 

S3S 

RS.a 
-'03 



(/J 

<! 

a 



lis. 

oj ^ 



•" -s 






t. 



3 









V .a 
-*^ a 

n 0: 



5 F^ o -3 



O 

& - 

o .2 



QJ h 



a 0! 



=« « :^5!«5 



S S " -!?!« 



M to 



"3 ^ 



.2; •■' 



« 00 03 



55 t: « -7* 'S T? 



.2 5 s 



03 n 



■g -S ■So£"S 

a ea »^ w a> ::; 

S 1 § "^ = a - •§ 

.2 a .2 S -2 2 -3 
■3 S -a o g J3 0.5 

S o S o b 600 a 



m2 
"ox: 



r a 

0303 



a S" — 

» .1 ° 

■S w 2 

I 1 I 

r* f~ C 

"S >»<J > 










•-« 


CO 


OQ 


a 


• 


>3 




•2 


2 


S 
a 






3 





00^ 


0-1 


3 

cr 
4^ 


t^ 








~,s 


3 


<0 

00 
l-H 



CO 

2 


"3 







•a 




■4^ 


bo 



5£ 




1 


V 


(M 


<u 


£i 


■3m 


on 


■•-> 




CS 


-PL< 


II 


n 








3- 


g 


■§ 


co-g 


K 


«P3 


2!§ 


^'i 


z 




•3 ■a 


^g 


!^-. 


w 


.S-, 


S 


ss 


S'SSga 


1 


l§ 


y 




ss 


♦J •^00 E ""* 

?22So 


y 





u 


ow 


00 


a 



S6 



REPORTS ON THE STATE OF SCIENCE. — 1918. 



a. 2 



I" -^ 

a 
o 



'^ .ii '^ 



>,^ 



a 

a S 3 m 

•C p; g .2 o 

i::^ EH ph 



^ la 



■= a 



^■S o 3 3 O , 



*^ 3 3 Sj 









OJ CO 



rz a 

a cia 
2&g 

Eh H 



•2 tr, 



'" « a 

a o ; 
.031 



s 3 
9 =3 
3 == 

(fl c3 

be b£) 
a a 






a ai? 
a q- 



H H 



o eo o 2 
x o a 






a a ca u a 
« EH fMH 



= S " 3 

! 2 O 0! 

« S S 

«} a a 

a ti ^ 

cs a a 

EHl-sl-5 



II 

.2 o 
00 

a a 

HEh 




,:•* a 



"" -. is 



a 2 



. O} t/1 ■ 

toj J^ C) «9 

la <D -.^ 10 

a s 



U 

a 



© aj cj ® 
o o 00 
25 ?5 !z;!z! 



;a :« 



O -J W 



CJ GJ CJ 4) 5j 4> CJ 

— a a a a fl ^ 

o o o o o o o 

2^ a 2;z;t5:5» 



so a 



a 
_a 
'■^ 
d 
o 
o 
I 



<§ 







00 « CO 
O 10 CO CC 
O C< C» —1 






_i _I — — t5 * 



r<1 



^ 



o. 

p 



a 

3 
P 



••s ? 



11 '^ 



rtaS 



^Q-S 



E a a 



60 • • 

a 
o 
u 

a " S 

3 ^ a 

^ CS - 
QJ O ■♦^ 

-3 « P3 S 

fe a3Ja 
X ^ aTi-T 



S 5^. 



Ki 1^ 



a 

■a 



W 2' 



c r3 -^ 



•a j; 



— a 



. W-a 
a OH 



^'.d S 



^ "a .a 

a P^ . -*^ 

■a ^4 a 

^ 3 -iS 

^ ;_ — ^ . 

* S a g" 
3-° 5,-° • 



a a; 



o o 

m a. 

wi 

a >> 

« QJ 



a '^ 






a 



w 



■2 e 
a > o; 



pH , a> 
lit crS 

■Sm° 
o-a CO 

h t^ * 

CLi <! 



bog 

C8<1 

S.a 
"I 

CO u 

■SEh 






PQ r 



•l I 



^ — 



w 



a-^ 

n T 2 a J o 

oj 02 ja a ,a to ^ 
Mr'-S a be a 

£cr»S3g' E 

g • Pi CO .a 



•M3- 

• ca , 

■a 3 

3*3 

P^ 

- ^Eh 
aco , 



g 



1^ 
Ji-SEh' 



fe " a °^ 

'-' a a^q 
a^« «' 
-.J =0 a -*j 

o. •-" S 

. ^ - 

-V. -^ to 

Eggg 

-a S o g 

S^ pa 



o 

a a) ^ 

a>J--S 
.2 oT a a 

5 Sco3 

rt a t- ^ 
S > 3a 



a 

C3 



W 



OS Q 

I— I 4J 



S a S" "w 



O 

13 



:z; :s 



■2§'g 

<u a.S 
.^ 03 a 

(D C3 






CO o 

3S 
^ a 

bb-S 
a § 



i^ .a 

bo "sJ 
.*^ c 

.a a r 

►; s \ 

O '^ . 

2.2 3 - 

ea *o '3 ffj ; 

^5ESc 

^ tc ; 



l-fise^^-lilll 



ta £} ^ -^ G 

00 -*-' -^ a o 



- i-i u 



h o 
■a ao 
•S tc 

22 6 
o^ a 

S a'o 

-^ +3 .a 
^ .2.2 

o 
a «3 M 

tO< m 



.2 

I s 

I « 

p o 

bo be 



'O .-I • CD 
Cd Ei) » 



.2 J 
o o 
° rl 

CO<lJ 

"3 'a >> 
■- S "S 

tn 3 '^.^ 
O— o 

.•go « 
(1,2 ■§ 

"gig's 

.a d « rt 



10 



CD o 



0.0 



3 
5 "3 

O 3j 

a £''3 

-•2S 
ca o_ 

3C0 a 

5 •^.2 in 
- » bf-s 
■^■35 a 

~ to "IJ u 
03 3 



2 o "•3, S 



t^ !^ 




IS 


a 


tSM 




P 


:2t. 




•1 


<" 


ta a 




U) 


43 ca 




m ca 




^ 




■^r? 


2 

•-1 


■S-2 




*« 2 


■s 


P.S2 




•&.-S 


f5 








13 ca 


r^ 


Leeds Geolo 
Leicester L 
1835 


.— 

3 


si 
ag 


00 


a 

1 

a 
3 



CORRESPONDING SOCIETIES. 



87 




a a ^ a ^ M 
""^ otc ►- 'S o 



=° .^S . 
—' a o 




Z » 



u u u a) 0} -w 
a s :: c a (3 
o o o o o 



a a 
o o 



o •» ^ 



a 3 " 
o o o 



=3 s 



^=5 ^ 



kO © o 
00 *o o 

■* o 



d '.a ca o o 

o w '^ *o to 

^ f-4 ri ^H CQ 






s .- 

S 3 



>) s 

to J4 
O CJ 

O _f 

- eg 

(^■^ 

ill 

■3 >>■ 

Saa' 
WPS- 
.2"S§ 



n 



3 



o 



" S 



O . — ' 

oj D. a 

ya q O* 

a gco 

■^ "m -lJ 



1 

o 



E-t 
o 



W »^ CO 

H -<1 






00 -e •a 

r- 3 o 

-^ j3 a 

tfl - 5 be cB 

Sffia 
1^ H us 



a 

as? 






13 



i >^l g 



O o rt 3 

., >< aM . 

aog a g- 

ej M '^ O to 



as 






« CQ 
CO o 
C4 iM 



C5 



O -*^ 



H 



2 S 



.2 o 



> 
13 






to 

a 



J5 

3 

Su 

.2 o >, 

U en -»3 

o <D fc; 

o .. .. 

Ra a 
£•00 

£^ a s 

►J Hi Hi 



a •« 



:§ .g 

1 I 



o 

00 

00 



■3 

o 
xn 

o 

'p. 
o 



U3 



00 
do" 



O 

CO -*3 









SP « '-s 



;5 


m 


s 




r^ 


-n 










^ 


iri 






<i> 


"3 


■s 

















rt 


!/J 




S 




^ 



CO *3 

■«j C6 

§1 
^^ 

.2 M 

^ a 

CO ^ 



to 
a 
» 

o 

a 
o 



a< 



Zff 



S a 

CO 3 



CO OJ 



6 



m 



I > 



o 

o 



a i5 



iSi 



a 4 
o *j ^ 
S art 
8- V 
Sfi a' 

.r= a « 
"■^ °Q 

(D "-I 

» n 



p c4 

a gi-5 
aS a 
ea „ a 

o 2 o 
12; s« 



p< .2 



Ph 



. cs a 
no's 





^« 



b; o 



M h 



o a 

to [« 

a a 

e8 cd 



■+3 O 

iH be 
V — 



a 

a 

— o 

o 5 to " 

E^ (^ GO ;^ 



OS a 

00 
t tlO 

>..2 
«a 



0) 3i»2 
3.52° 

fc a H a> 
^ «&« 
o-^ a <u 
•> a -a.ij 

C * 0-a 

^ a — ir 



a 



"53 « 



o 

OQ 






W a. 1.2 

- lis 

- « a 
gto.W 3 

•S ►- TI — -^ 

.05 a »! rt 



90 o 
-^ a 



a rt i;*^ 
rt rt CO ^ :^ 

a aa a 



3 
a 



a», 

O O"^ o 

2;^ S 



o J3 '^- 5 a 

" a -■a 
-•sis a 



!z; » 



o 

o 

3 
3 

CS 



8 ^ 






cC 



.a 
o 



88 



REPOETS ON THE STATE OF SCIENCE. — 1918. 



O OD 

B O 

a o 



a 
I 



■a 



^ 

^ 






s 



20 



■d-<l 



=3 ^i^. 

3 •-■Si' 
a = o S 

!5 si 3 
a " S 

flow 

M >».A r« bo 



Is 



o 2 >»t«) 

•r^ CO .— ■ a 

9 5 <=> S 

P o c« P 



C3 ^ 

•a a 



o a 
-^s . 

•»-< J- ra «J 
o oj 5 -M 

.2-sgg. 

■so-- 

cS'^cacS OS OJ OJ C3 

Bg>HS a a o a 

ea.Sd:3 is o o as 

fc*oo ^ ^ ^ ^ 

tn ni^ EH h m H 



5 a < 
•2qS 



CO rt 



I 1.1 

*» .^ -.a 

o ts t> 

C3 V 03 

en a> en 

a o a 

ee O 03 

H PhH 



:^ OS 

0! 3 

S 3 

5 a 






B 
-i 3 

a 



^ "O _ •» 



a 



00 0} 
Be fl 
00 o 



■a 
too a g 
,00^ » 






a a a 
00 o 



lA O lA 



o o 



■a 4J 

O o .* O O (S o 
O 00 00 00 CO 'o o 
M .-I --I M_ X ■* 

§4! 



a 
& 
o 
Eh' 



',3 'o 

c6 e te 



« 5 

•5 w 



■a S 
a -t^ & 
3 3 , 



-o 

a« 

QJ ©*^ fl 

is § a 

8.2 § 
a**" 

,««' 3 b 
i; S.M a 

+3 - b 03 

u 0} a r^ 
c8 «ri a 



03 S 

a © 



• 5 



t> s 







rf 


r^ 


s 


.a 






W 


J= 


2: 















ucn.a 








U 


m 


a 


;__1 


or/3 


<1 


ja 








p 



cb 



l2 *H ? 0) 

• .2 a -g a S 
ca aj ^' « "" 



bo 
a 
p. 

03 

o 



03 

a 

M 



a 



a o. 






^ 'So 





t=S- 


SI 

a 


■43 


o;ja 


V 


jacQ 


H 





-Eh 


m 


&: 


a3_: 


n 




M'o 







a-W 


J4 





spa 








3 3 


(H 


•rSW 


OS 


a 


lota 


§ 


5fe|5 


s 


P4 


<it^ 


a 



oa 
Q 



EH 




^ .^ 






f^ 


!a 00 1^ 


.a 
0. 


1 ^1 




t. S 






J3 


^S«^§ 


PH 


S-.&»2 




affordshire an 
ing Engineers 
Natural Histo 
Geographical 





>> i2 



o 3 



S3 >- 

n. <J 
o 

3 « 






^ 3 CO 



CO 00 

OD .-H 



13 

►3 



C/l 






) .5 >»Ti 



i EhEh 



J .1 

is wo ■: 

a Is' 
•cS?.2i 



a 



o o 



.2-3 

6(1 S 


C! 






.b.t 




MM 







tHtH 






^ 

'« 
« 



00 



tU) 

a 



3 a gi^ 
"2 i 
^J-'S i. a 
- ^ ^H a 



a 



o 



ro 



03 



Z !zi 



fe: 



« 



03 






a g^ 
'-ZB" 



&a 








_3w 


a 


.2 s 


m 


^:j 


IS 


;^ 


Is 


. 


■o 




bo 


a 












&> 




>i 


<fl 
















•G 


1-3 




03 


'3 




d 


a 




0! 






'u 


J2 




a 


a 










s 


^a 


■^ 


-13 


i.i 


00 




w d 










5 


30 















H 


t?^ 


<u 


-a 

a 
IS 


If 


1^ 


H 


^ a 


s 




0.2 


^ 


g 


fc 3 


^9 


03 


M 


cq 



CORRESPONDING SOCIETIES, 



89 



a t>> 

(-1. "^ 



" K hi 
W 2-3 



to g 



IwS 



^ bo 






O H ee 



- . o 

d a ^ .to 

O O 2 >.6p 

n CO t-i d (U 

a a O 3 o 

^- fc< QJ " fc4 



• 2 « 

>*g a 

= 1.2 



& o =^ 

O IH ^ 



13 

a 



2 LZ " 

o - 2 3 

o c S S 

o (fl 2 o 



all I 



^ M^ 



CM M 



3 

CS £3 3 

O td J- i- S 

ja 3 o o o 

rr, ^ <a V a 



p? 



•f 




-v 


'e'e 


'3 






«© 


CO CO 


^ «« •« 


•ejus us 


c^ 




CI 



O O -^ «5 



US 

.•«■§ 

M to 



la 



S I - 



u V u a; 

a a a a 

o o o o 

lz;ZK Z 



!2; fc 



aaa a a a a aS 
ooo o o o oo. 
ZS5Z ;z5 » a aZ^ 



!2i Z !a 



o 



!2; 



V V o 

aaa 
ooo 



g !3 



o oo 

■-- CO 



OOO 

o w o 

09 1^ 



CO 

.D © 

«oo 5^00 

o a 

o ta 






a 

a 
W 



Sb5m 
■•I'a - 

a d „ 
mW^ 
*S.-a 

CO M > 

■a « g a 

a o a=5 
o o o a 
ZOO) S 

la"a 
^ a <u 3 

'^ O J3Q 



2 < 



o 

Hi 



•g w 



=sO 



■a 
o 
P3 



.Kl ?^ 






■3 
D 



00 

Sen 






2 be . 

1^ - a 



-a rou 

*^ 03 O 

to ^-,0 

- u h 

■as •• 



J ".2 *^'" 

^ a o -»3 

" o .g 

£ ^S h 

02 » f> tc 

ja "3 S 

t>o= . 

B^a" .2 

"J I °. 

g' rt B H 

S*^ a 1-5 

-•Ipl 



ja 



.a 



■s|s 
g ESS 

Oh. a) 



a o h 
o c£ 
■S-g M 
o a 3 

o a;a 
^a-§ 



CO 



"S 




a 




01 






Fi 


a 





■s 


W 



•< g 






aa , 

^ ^ o 



_C0§ 

g4S 



H 

a 
o 

c. 
a 



"^ja a d3 

•g i5 -o C g 

mW3W S 

S S ;a 



2 a 



=3 9 >! 

Ed O 0} 

W|a 

i-S a 
g|M 

-fc;>.a • 






<! W 



bO 

S 
. .'^ 

S 5 a 
a.gH 

o _'§ 

02 a,a 

« go 

So 

= iS « 

»nao 

a ti - 

.2 ^S 
;S cu .2 

en g t> 

aQ 
^•■^^ 

Ph>-! 



^■- ^ -3 



M 2 W 



a 



■^a 



c^aSa" 



•3 '^^ 



n 






a. 
8 



£■ 

^ 






a e 



5g s 

'•i-i oi 

->: •- 



a 



.^ " 



•■^l 



3 00 I 



H'=5 



^ la a 
ZS S 

sil 

'O o ^ 



" iH a 

3 C3 

*< ■♦^ -, 

2§ « 

'o a 4) 

a -.-- — 

t-. ^ QO 

■si ■« 



i>>ta 
.»^ a 
.2 o 



ooj -3- 



s 2 " 

• --2 ° 

II ^ 

.el's o 

•0-- 2 

to .^ o a 

<»Pho 2 

>.B q ro 

" ^ a "3 

■gS-w g 

rS 2 « 

'"Si .0 

•2 o,a ^ 

goo's R 



tsg 



CO -t^ 

. o <u 

Oi *"" 



v" "S >-" 



3§ 5 W 



-"■' a -.a -g 



a .2 "S " -^ 
?.otn CO >. 
^""Sa" 



i^ 2 a 
•go « 

«lj to >-! 

to -a 
j«] oj-a 

.2 6 «I 

C ^ tit 



^ £ 



>: 3 S 3; ■.) 



3oD.a -n 
■*^ ^ -*^ f^ 

«s g a 

t» S-«o3 



" a CO CU - CU ■ CU 



00 w 

tDO .CJ ^^ 

■g-a-S 
■3|3 W 

^ -tj bi 
CS u a 

2"C-S 

SO a 

t. H ta 
"3a 

a Oh3 

o.g- 

.£.2g 



■a 



a S w S^ . .2 

o O . OJ oj o 

J CO -a o a o 

_ m'S CO H m o 
,a o ^^ • 05 ta 

ga S-2§.':a 

mW «.a a'g.a 

'- oj a. J, o o 

.. 0) a o^ "^t" 

a aS o ;o-S a 

'2,5'S? > o» 
gZgfcgtog 

►J a a PLi 



■5 o 

O • • -PLl 

S S 'a 

w t» « 

•a '^ • a 

2 5, 

<J .§»£;. 

■a " -SSS 

a 2 O'-'x: 

S S " XiS 
. •= -9 w 

_■ ^ cs a 

« a fc- =:;^- 

ao a 



J3 

a 
o 



a 
P 
t», 
o -a 
.■a a 
.a *^ 

^c»'2 

a kT a 

0.2- 

x> o o 

M O O 

a CO .a 

u '^ 

CO 



CO 



as 331? 
!^.2l?§i2 

S-S "£■.■§ 

lias's 

Ms « a 



CQ 

2 



a 

a 
O 



•231 



90 REPORTS ON THE STATE OF SCIENCE. — 1918. 



Catalogue of the more important Papers, especially those referring to 
Local Scientific Investigations, published by the Corresponding 
Societies during the year ending May 31, 1918. 

* * This Catalogue contains only the titles of papers published in the volumes or 
* parts of the publications of the Corresponding Societies sent to the Secretary of 
the Committee in accordance with Rule 2. 

Section A. — Mathematical and Physical Science. 

Abbut, C. G. The Sun and the Weather. ' Joum. Royal Astr. Soc. Canada,' xi. 

dOsUie. 1917. 
AiNSLiE, Maurice A. The Measurement of Magnifymg Power. A Note on Mr. 

Bale's paper. ' Joum. Quekett Mic. Club,' xiii. 315-320. 1917. 
Alsop J C Summary of Meteorological Observations and Meteorological Tables, 

1917.' 'Report Marlb. Col. N. H. Soe.' No. 6C, 48-68. 1918. 
Bale, W. M. Note on the Measurement of Magnifying Powers. ' Joum. Quekett 

Mic. Club,' xin. 307-314. 1917. 
B\SSETT Rev H. H. TiLNEY. Returns of Rainfall in Dorset m 1916. ' Proc. Dorset 

" N. H. A. F. C xxx\T[n. 81-92. 1918. 
Bl.vke, F. L., and W. E. W. Jackson. A New Form of Clock Synchronizer. ' Joum. 

Royal Astr. Soc. Canada,' xi. 175-177. 1917. 
BoHLE, H. The Theory of Automatic Regulations. ' Trans. Royal Soc. South 

Africa,' VI. 271-287. 1917. 
Beighton and Hove Natural History .\j.-d Philosophical Society. Meteorology 

of Brighton. ' Report Brighton and Hove Nat. Hist. Phil. Soc' 1916-17, 35-36. 

Brotheeton, B. British Rainfall, with Special Reference to Worcestershire. Trans. 

Worcestershire Nat. Club,' vi. 202-221. 1917. 
Campbell, J. W. The Determination of the Date of Easter. ' Joum. Royal Astr. 

Soc. Canada,' xi. 367-375. 1917. 
Campbell, W. W. Two Great Problems of the Universe. ' Joum. Royal Astr. 

Soc. Canada,' xi. 281-291. 1917. 
Cajipbell-Bayaed, Francis. Report of the Meteorological Committee. 1916. 

'Trans. Croydon N. H. Sci. Soc' xm. 137-146, and Appendices, 62 pp. 1917. 
Cannon, J. B. The Orbit of the Spectroscopic Binary Boss, 3138. ' Joum. Royal 

Astr. Soc. Canada,' xii. 92-94. 1918. 
A Note on the Spectioim of Lightning. ' Joum. Royal Astr. Soc. Canada, xn. 95- 

97. 1918. 
CAR\i)oc and Severn Valley Field Club. Meteorological Notes. 'Record of 

Bare Facts,' No. 26. 24-41. 1917. , . . o r, .-, • 

Chant, C. A. The Variable Star Tl' Virgmis. Joum. Royal Astr. Soc. Canada, 

xn. 47-56. 1918. 
Cheshire, Horace F. The Sound of the Guns. ' Hastings and East Sussex Natural- 
ist,' n. 229-230. 1917. , ^ , ,^ ^ 
Christy, Miller. The Mid-Essex Wind-msh and Whirlwind of 27th October, 1916. 

' Essex Naturalist,' xvni. 135-145. 1917. 
Coates, Henry. Abstract of Meteorological Observations, Perth, 1916. Proc. 

Perthshire Soc Nat. Sci.' vi. CLXXX^^I.-CLXC. 1917. 
Meteorological Observations, Perth, 1916. ' Proc. Perthshire Soc. Nat. Sci. 

VI. CLxxxvin.-cxci. 1917. . 

Craw, James Hewat. Account of Rainfall in Berwickshire during 191 i. History 

Berwickshire Nat. Club,' xxm. 412. 1918. 



CORRESPONDI>'G SOCIETIES. 91 

<Jress\v£LL, Alfeed. llecords of Meteorological Observations taken at the Observa- 
tory, Edgbaston, 191G. 28 pp., and folding table. 'Birui. and Mid. Inst. Sci. 
Soc." 1917. 

Cbommelin, a. C. D. Are the Spiral Nebula- External Galaxies 't ' Joum. Koyal 
Astr. Soc. Canada,' xii. 33-46. 1918. 

Denning, W. F. Real Paths of Bright Meteors seen in 191 G. ' Joum. Royal Astr. 
Soc. Canada,' xi. 178-179. 1917. 

A Few Notes on Amateur Observei-s and Observations. ' Journ. Royal Astr. 

Soc. Canada,' xii. ir)7-159. 1918. 

Fox, Wilson Lloyd, and Joshua Bath Piuli.tvs. Report of the Observatory 
Committee of the Royal Cornwall Polyteehnir Soriety, with Meteorological Tables 
and Tables of Sea Temperature for the year 1916, with Lustrum Tables for Sea 
Temperature, 1911 to 1915. ' Report Royal Cornwall Polytechnic Boc' ni. n.s. 
11 pp. 1917. 

Fkiend, Dr. J. Newton. Notes on the Rainfall of the Severn Basin and on Dis- 
solved and Suspended Materials carried past Worcester in the Severn. ' Trans. 
Worcestershire Nat. Club,' vi. 246-248. 1917. 

■CtR.4h.a,m, T. S. H. Measurement of Radial Velocities of Stars by means of the Ob- 
jective Prism Spectrograph. ' Joum. Royal Astr. Soc. Canada,' xn. 129-152. 
1918. 

HALD.4NE, Dr. J. L. The Spontaneous Firing of Coal. ' Trans. Inst. Min. Eng.' 
LUi. 194-204. 1917. 

Halliday, Mark (N. England Inst. Eng.). The Flow of Water in Syphons. ' Trans. 
Inst. Min. Eng.' liv. 107-109. 1917. 

H.uiPER, W. E. The Albany Meeting of the American A.strcnomical Society. 
' Journ. Royal Astr. Soe. Canada.' xi. 333-340. 1917. 

Orbits of Three Spectroscopic Binaries. ' Joum. Royal Astr. Soc. Canada,' 

XI. 341-345. 1917. 

Hass.uid, a. R. Summer Observations. ' Journ. Royal- Astr. Soc. Canada,' xi. 
376-379. 1917. 

Seen in a Fourteen Inch Reflector. ' Joum. Royal Astr. See. Canada,' xi. 

417-420. 1917. 

Henderson, J. P., and A. F. Hunter. The Solar Halo of Febraary4th, 1918. ' Joum . 

Royal Astr. Soe. Canada,' xii. 153-156. 1918. 
Hodgson, E. A. A Phenomenon and its Explanation.' 'Journ. Royal Astr. Soc. 

Canada,' xi. 297-299 1917. 
HoPKiNSON, John. The Great Storm of the 28th of March 1916, in Hertfordshire. 

'Trans. Herts. N. H. S. F. C xvii. 5-12. 1918. 

- The Weather of the Year 1916 in Hertfordshire. ' Trans. Herts N. H. S. F. C 
xvn. 17-32. 1918. 

Hunter, A. F. Distorted Solar Halos. ' .Journ. Royal Astr. Soc. Canada,' xn. 

1-10. 1918. 
Johnstone, Dr. Jas. The Gulf Stream and the Weather. ' Joum. Manchester Geog. 

Soc' xxxm. 23-30. 1918. 
Klotz, Otto. Magnetic Results 1916. ' Joum. Royal Astr. Soc. Canada,' xi. 

208-212. 1917. 

The Rainbow. Mourn. Royal Astr. Soc. Canada.' xi. 292-296. 1917. 

The Earth and Population. 'Joum. Royal Astr. Soc. Canada,' xii. 11-14. 

1918. 

Locating Submarine Faults. ' Journ. Roval Astr. Soc. Canada.' xii. 57-CO. 

1918. 

Lawson, Gr.uiam C. Meteorological Report. 'Trans. N. Staff. F. C.'li. 123-127. 

1917. 
McAbtiiur, J. J. Notes on an Exploration through the Yukon, along the Base of 

the St. Elias Alps. ' Journ. Royal Astr. Soc. Canada,' xi. 318-332. 1917. 
M.\,RKH.\M, Christopher A., and R. H. Primaa'ESi. ]\reteorological Report. ' Journ. 

Northants N. H. Soc.' xix. 51-54, 78-81, 95-98. 1917, 1918. 
Marriott, Major R. A. The Last Glaciation and the Submerged Forests. ' Joum. 

Torquay N. H. Soc' ii. 163-176. 1918. 
Morton, Prof. W. B. The Flight of a Bullet, ' Proc Belfast N. H. Phil. Soc' 

1916-1917. 73-76. 1918. 



92 EEPORTS ON THE STATE OF SCIENCE. — 1918. 

Motherwell, R. M. The Total Solar Eclipse, June 8, 1918. ' Jouni. Royal Astr. 

Soc. Canada,' xii. 160-168. 1918. 
Mum, Sir Thomas. Note on Palmstrom's Generalisation of Lamp's Equation. 

' Trans. Royal Soc. South Africa,' n. 323-326. 1917. 
MusHAM, J. F. Meteorological Notes from Selby. ' The Naturalist for 1917,' 249- 

251. 1917. 
Patekson, John A. The Greatest Mathematical Philosopher. ' Journ. Royal 

Astr. Soc. Canada,' xi. 155-174. 1917. 
Patterson, J. Long-Range Forecasting and other Weather Illusions. ' Joum. 

Royal Astr. Soc. Canada,' xi. 261-280. 1917. 
Peal, H. W., and W. R. Hicks. Meteorological Notes for the year 1916. 'Fortieth 

Report Ealing Sci. Mic. Soc' x. 1918. 
Rambaut, Dr. Arthur A. Meteorological Report, 1916-17. 'Report Ashmolean 

Nat. Hist. Soc' 1917, 16-17. 1918. 
Rutherford, J. Extracts from Weather and other Nature Notes taken at Jarding- 

ton during 1916. ' Trans. Dumfriesshire and Galloway N. H. A. Soc' v. (Third 

Series), 143-151. 1918. 

Weather and other Notes taken at Jardington during 1917. 'Trans. Dum- 
friesshire and Galloway N.H. A. Soc' v. (Third Series), 223-229. 1918. 

Simons, Lewis. Ionization of Gases and the Absorption of Rontgen Rays. ' Trans. 

Royal Soc. South Africa,' vi. 311-322. 1917. 
Steadavorthy, a. Aurora Borealis : Display of August 21, 1917. 'Joum. Royal 

Astr. Soc. Canada,' XI. 365-366. 1917. 

— Some Problems in Photography. 'Journ. Royal Astr. Soc. Canada.' xi . 380- 
384. 1917. 

Steavart, R. M. Clock Synchronization. 'Joum. Royal Astr. Soc. Canada.' %j. 

232-235. 1917. 
Stupart, Sir Frederic. Is the Climate changing ? ' Journ. Royal Astr. Soc. 

Canada,' xi. 197-207. 1917. 
Swinton, a. E. Meteorological Observations in Berwickshire for 1917. History 

Berwickshire Nat. Club,' xxiii. 411. 1918. 
Van dbr Lingen, J. Steph. Radial Lines in Rontgen Interference Patterns. ' Trans. 

Royal Soc. South Africa,' vi. 203-204. 1917. 
VAN Maanen, Adriaan. The 150-foot Tower Telescope of the Mount Wilson Solar 

Observatory. ' Joum. Royal Astr. Soc Canada,' xi. 223-231. 1917. 
Waleord, Dr. E. Meteorological Observations in the Society's District, 1916. 

' Trans. Cardiff Nat. Soc' xLix. 1-17. 1917. 
Watson, Albert Durrant. Astronomy : A Cultural Avocation. (Retiring President's 

Address.) ' Joum Royal Astr. Soc. Canada,' xn. 81-91. 1918. 
Watt, Andrew. Rainfall Records for the South-Westem Counties for tfte year 

1916. ' Trans. Dumfriesshire and Galloway N. H. A. Soc' v. (Third Series), 

152-153. 1918. 
Whitmell, C. T. The Rainbow. 'Journ. Royal Astr. Soc. Canada,' xn. 16-16. 

1918. 
Yorkshire Philosophical Society. Meteorological Returns for 1916. ' Report 

Yorkshire Phil. Soc' 1916, xix-xxiv._ 1917. 
Young, Reynold K. Spectroscopie Binary Orbits of 40 Aurigse, ir Arietis, Bess 

5996. ' Journ. Royal Astr. Soc. Canada,' xi. 213-216. 1917. 
■ Miscellaneous Radial Velocities. ' Journ. Royal Astr. Soc. Canada.' xi. 

217-222. 191 \ 



Section B. — Chemistry. 

Blunt, T. P. Notes on Obsidian and Natron from East Africa. ' Trans. Caradoc 

and Severn Valley Field Club,' VI. 97-99. 1917. 
Drakeley, Thomas James. (Manchester Min. Geol. Soc.) Coal-washing : A 

Scientific Study. ' Trans. Inst. Min. Eng.' liv. 418-457. 1918. 
Friend, Dr. .1. Newton. Oils — Their History and Value. ' Trans. Worcestershire 

Nat. Club,' VI. 231-236. 1917. 
Garnett, H. Some Notes on Alcohols. ' Trans. Manchester Mie. Soc' 1916. 

62-65. 1918. 



COHKESPONDING SOCIETIES. '.lii 

Painter, Hubert. Carbon ; An Outline of the Chemistry of the Element and a 
Few of its Compounds. ' Proc. Bournemouth Nat. Sci. Sec.' viii. 89-95. 1917. 

The Uses of Carbon. ' Proc. Bournemouth Nat. Sci. Sec.' viii. 114-123. 1917. 

Pettigrew, R. Notes on Residues obtained from the Treatment of Substances 

with Acids. ' Trans. ^Manchester Mic. Soc' 191(5, 50-54. 1918. 
RiNDL, M. Note on the Occurrence of Daphnin in the Arthrosolen. ' Trans. Royal 
Soc. South Africa,' vi. 295-290. 1917. 

Section C. — Geology. 

Baddeley, W. St. Clair. President's Address : Salt — Its Origin, Uses, and Folk- 
lore. ' Proc. Cotteswold N. F. C xix. 205-211. 1918. 

B.4RKE, F. Geological Report. -Trans. N. Staffs. F. C li. 119-121. 1917. 

Bather, Dr. F. A. Hi/dreinocrinus verrucosus n. sp., Carboniferous, Isle of Man. 
' Trans. Glasgow Geol. Soe.' xvi. 203-206. 1917. 

Some British Specimens of Vlocrimis. ' Trans. Glasgow Geol. Soc' xvi. 

207-219. 1917. 

Bell, Alfred. A List of Type and Figured Specimens in the Geological Gallery, 

Ipswich Museum. ' Joum. Ipswich F. C v. 41-49. 1917. 
BoswELL, Dr. P. G. H. The Geology of the Woodbridge District (Suffolk). ' Jouni. 

Ipswich F. C V. 1-12. 1917. 

Underground in East Anglia : Recent Borings and what they Teach. ' Journ. 

Ipswich F. C V. 13-33. 1917. 

Cantrill, T. C, and G. M. Cockin. Neolithic Flints from a Chipping Floor at 
Cannock Wood, near Rugeley, South Staffordshire. 'Trans. N. Staffs. F. C 
LI. 85-98. 1917. 

CoNACHER, H. R. J. A Study of Oil Shales and Torbanitcs. ' Trans. Glasgow Geol. 
Soc' XVI. 164-192. 1917. 

Dron, R. W. (Min. Inst. Scotland). The Occurrence of Coking Coal in Scotland. 
' Trans. Inst. Min. Eng.' lv. 61-68. 1918. 

Geikie, Sir Archibald. A Yorkshire Rector of the Eighteenth Century [Rev. John 
MicheU]. ' The Naturalist ' for 1918, 7-24. 

Gregory, Prof. J. W. The Geology of Phosphates and their Bearing on the Con- 
servation of Mineral Resources. 'Trans. Glasgow Geol. Soc' svi. 115-163. 1917. 

Thomson's Genera of Scottish Carboniferous Corals. ' Trans. Glasgow Geol. 

Soc' XVL 220-243. 1917. 

HiOKLiNG, Dr. George (Manchester Geol. Min. Soc). Contribution to the Micro- 
petrology of Coal. 'Trans. Inst. Min. Eng.' Liii. 137-181. 1917. 

The Geology of Manchester as revealed by Borings. ' Trans. Inst. Min. Eng.' 

Liv. 367-415. 1918. 

HiNCH, J. de W. The Development and Decay of the Irish Sea Glacier. ' Irish 

Naturalist,' xxvii. 53-63. 1918. 
Jenkins, F. W. (N. England Inst. Eng.) Little Namaqualand and its Possibilities 

as a further Copper-producing Country. ' Trans. Inst. Min. Eng.' liv. 7-8. 1917. 
Kendall, Prof. Percy Fry (Midland Inst. Eng.). Note on the Correlation of 

certam Seams in the Yorkshire Coalfield. 'Trans. Inst. Min. Eng.' liv. 67-71. 

1917. 

On the Splitting of Coal Seams by Partings of Dirt : Part I. Splits that rejom. 

' Trans. Inst. Min. Eng.' liv. 460-475. 1918. 

Latham, Baldwin. Records of Underground Water and Croydon Bourne Flows. 
'Trans. Croydon N. H. Sci. Soc' vin. 113-125. 1917. 

Leitch, p. a., and Dr. A. Scott. Notes on the Intrusive Rocks of AVcst Renfrew- 
shire. ' Trans. Glasgow Geol. Soc' xvi. 275-289. 1917. 

Lister, J. H., and J. f . Stobbs. Erratics in Coal Seams, with Special Reference 
to New Discoveries in North Staffordshire. 'Trans. N. Stafls. F. C li. 33-47. 
1917. 

Lowe, Harford J. The Caves of Tor Bi-yan, their Excavator. Excavation, Products, 
and Significance. ' Joum. Torquay N. H. Soc' ii. 199-213. 1918. 

Macnair, Peter. Notes on the Microscopical Characters of the Blackbyre Lime- 
stone in the West of Scotland. ' Trans. Glasgow Geol. Soc' xvi. 290-304. 1917 . 

Neilson, James. The Auld Wives' Lifts. ' Trans. Glasgow Geol. Soc' xvL 193- 
292. 1917. 

H 



94 REPORTS OX THE STATE OF SCIENCE.— 1918. 

North, F. G. The Minerals of Glamorgan. ' Trans. Cardiff Nat. Soc' XLix. 18- 

51. 1917. 
Odling, M. Third Report of the Fossil Fauna of the Oxford District. ' Report 

Ashmolean Nat. Hist. Soc.' 1917, 43-60. 1918. 
Pbeston, H., and A. E. Teuemajs. Oolite Grains in the Upper lias of Grantham. 

' The NaturaUst for 1917,' 217-218. 
Rankix, W. Munk. Geology of Carbon. ' Proe. Bournemouth Nat. Sci. Soc.' 

vra. 108-114. 1917. 
Reynolds, Dr. S. H. The Carboniferous Limestone Series of the Area between 

CUfton and Clevedon. ' Proc. Bristol Nat. Soc.' iv. (Ser. 4), 186-197. 1918. 
Sawyer, A. R. (N. Staffs. Inst. Eng.). The South Rand Goldfield. Part II. ' Trans. 

Inst. Mn. Eng.' liv. 93-100. 1917. 
Sheppaed, T. a New Species of Lima from the English Chalk. ' The Naturalist ' 

for 1917, 309-311. 
Bibliography. Papers and Records relating to the Geologj' and Palseon- 

tology of the North of England (Yorkshire excepted) during 1917. 'The 

Naturalist ' for 1918, 169-171. 
Smallwood, G. W. Flint and other Stone Implements f oxmd at Mary Tavy, Devon.' 

' Proc. Prehistoric Soc. East AngUa,' n. 349-351. 1917. 
Sjiith, Reginald A. Plateau Deposits and Implements. ' Proc. Prehistoric Soc. 

East Anglia,' n. 392-408. 1917. 
Staikier, Dr. X. The Rubble-Drift of Eastbourne. ' Hastings and East Sussex 

Naturalist,' ii. 238-245. 1917. 
Stobbs, J. T. Annual Address : Progress in Geologj'. ' Trans. N. Staffs F. C li. 

15-31. 1917. 
Taylor, P. W. Observations on the Local Distribution of Glacial Boulders. ' Trans. 

N. Staffs. F. C LI. 71-75. 1917. 
Tyreell, G. W. The Igneous Geology of the Cumbrae Islands, Firth of Clyde. 

' Trans. Glasgow Geol. Soc' xvi. 244-274. 1917. 
Walker, A. R. E. The Granite Area of the Schapenberg, Somerset West. 'Trans. 

Royal Soc. South Africa,' la. 193-202. 1917. 
Walkee, G. Blake (Midland Inst. Eng.). The Areas and Deposition of the Coal- 
fields of Western Europe. ' Trans. Inst. Min. Eng.' Liv. 77-83. 1917. 
Warren, Hazzledine. The Study of Pre-Historj' in Essex, as recorded in the 

Publications of the Essex Field Club. Presidential Address. 'Essex Naturalist,' 

xvm. 145-186. 1918. 
Whitaker, W. The Wickham Bourne. ' Trans. Croydon N. H. Sci. Soc' vm. 127- 

132. 1917. 
WooDHEAD, Dr. T. W. Occurrence of Boulder Clay at Hudderefield. ' The Naturalist' 

for 1917, 219-232. 

Section D. — Zoology. 

Adkin, Robert. The Weather of 1916 and the Occurence of some of the commoner 

Butterflies at Eastbourne. ' Proc. South London Ent. N. H. Soc' 1917-1918, 11. 

1918. 
Aiken, Rev. James. Some Observations on the Occun-ence of C^dex pipiens in 1917. 

' Trans. Dumfriesshire and Galloway N. H. A. Soc' v. (Third Series). 183-187. 

1918. 
Alsop, J. C. Report of the Ornithological Section. ' Report Marlb. Coll.' 66, 40^2. 

1918. 
Barclay, W. Annual Address : The Fifty Years of the Society's Existence. ' Proc. 

Perthshire Soc Nat. Sci.' vi. cl.-clix. 1917. 
Bickerton, William. Notes on Birds observed in Hertfordshire during the year 

1916. 'Trans. Herts. N. H. S. F. C xvn. 35^6. 1918. 
Bolam, George. The Fishes of Northumberland and the Eastern Borders : Part 

II. ' Historj' Berwickshire Nat. Club,' xxm. 250-304. 1918. 
Bon.a.parte-Wyse, L. H. Notodonta bicoloria in Co. Kerry. ' Irish Naturalist,' 

xxvL 164-165. 1917. 
Booth. H. B. Bottle-nosed Dolphin {Tnrsiops tussio) caught off Walney Island. 

'The Naturalist' for 1917, 300-301. 
Boycott, Dr. A. E. Pahtdestrina jenkinsi at Elstree. ' Trans. Herts. N. H. S. F. C 

XVI. 276. 1917. 



CORRESPONDING SOCIETIES. 95 

Brade-Bieks, Hilda K., and Rev. S. Graham Bkade-Birks. Notes on Myiiapoda, 

vin. Kecent Additions to the Irish Fauna. 'Irish Naturalist,' xxvu. 27-29. 1918. 
BucKSTONE, A. W. Notes on Zygcena fiUptndulce, Z. trifolii, and 2r. fonice; ce. ' Proc. 

South London Ent. N. H. Soe.' 1917-18, 1-4. 1918. 
Bullock-Webster, Rev. Canon G. R. The Characese of the Rosses : West Donegal. 

' Irish Naturalist,' xxvir. 7. 1918. 
BuRKiTT, J. P. Note on the Long-eared Owl. ' Irish Naturalist,' xxvi. 161-163. 

1917. 
Burrows, Rev. C. R. N. The British Psychides. ' Proc. South London Ent. N. H. 

Soc.' 1917-18, 27-30. 1918. 
BuTTERFiELD, W. RusKix. The Marine MoUusca of Sussex. ' Hastings and East 

Sussex Naturalist,' ii. 231-237. 1917. 
Notes on the Loeal Fauna, Flora, etc. for the year 1916. ' Hastings and East 

Sussex Naturalist,' ii. 246-250. 1917. 
Caradoc and Severn Valley Field Club. Zoological Notes. ' Record of Bare 

Facts,' No. 26, 13-22. 1917. 

Entomological Notes. ' Record of Bare Facts,' No. 26, 23. 1917. 

Carpenter, Prof. Geo. H. Some Notes on the Dulalin Gorilla. ' Irish Naturalist,' 

xxvL 125-130. 1917. 
Carter, C. S. Holocenc Shells at Ruckland, near Louth, Lincolnshire. ' The 

Naturalist ' for 1918, 119-123. 
CHApu.'iN, Dr. T. A. Apterousness in Lepidoptera. ' Trans. London N. H. Soc' 

1916, 49-73. 1917. 
Co.A,TES, H. Note on a Sub-Fossil Elk's Horn found at Methven in 1801. ' Proc. 

Perthshire Soc. Nat. Sci.' vi. clex.-clxi. 1917. 
Cockayne, Dr. E. A. Presidential Address. [Mendelism.] ' Trans. London N. H. 

Soc' 1916, 31-37. 1917. 
CoLGAN, Nathaniel. A Note on Pedinaria Koreni from Dublin Bay. ' Irish 

Naturalist,* xxvi. 136-138. 1917. 
CoLLiNGE, Dr. Walter E. PorceUio Eathkii, a Woodlouse new to the Irish Fauna 

' Irish Naturalist,' xxvii. 1-2. 191 
Cooper, W. Omer. Some Rare and Interesting Local Isopods. ' Proc Bourne- 
mouth Nat. Sci. Soc' vm. 72-81. 1917. 
Crawley, W. Cecil. Ants and Aphides in West Somerset. ' Proc. Somersetshire 

A. N. H. Soc' Lxn. 148-163. 1917. 
Curtis, W. Parkinson, and E. Harker Curtis. Report on the Batley Ornitholog- 
ical Collection. ' Proc Bournemouth Nat. Sci. Soc' vin. 66-69. 1917. 
Day, F. H. Cumberland Dragonflies. 'The Naturalist' for 1917, 357-358. 

Cumberland Coleoptera in 1917. 'The Naturalist' for 1918, 73-74. 1918. 

Dixon, Annie. Report on Protozoa collected on rambles, 1916. ' Trans. Manchester 

Mic Soc' 1916, 114-119. 1918. 
Donisthorpe, Horace S. J. K. Elater praeustus F., an Irish Beetle. ' Irish 

Naturalist.' xxvi. 99-100. 1917. 
Else, W. J. Curiosities of Bird Life. ' Trans. Worcestershire Nat. Club,' vl 281-293. 

1917. 
Falconer, Wm. Abnormal Spiders. ' The Naturalist ' for 1917, 232-233. 1917. 
Fletcher, J. H. Wire-worms. ' Joum. Northants N. H. Soc' xix, 76-77. 1917. 
FoRDHAM, W. J. Yorkshire Coleoptera in 1917. ' The Naturalist ' for 1918, 99-102, 

135-137. 
Foster, Arthur H. A List of Birds which have occurred in North Hertfordshire, 

with Notes on each Species. ' Trans. Herts. N. H. S. F. C xvi. 189-220. 1917. 

A List of Macro-Lepidoptera occurring in North Hertfordshire, with Notes on 

each Species. ' Trans. Herts. N. H. S. F. C x^^. 237-258. 1917. 

Foster, Nevin H. The Winter of 1916-17 and its Effect on Bird-life in Co. Down. 
'Irish Naturalist,' xxvl 118-120. 1917. 

The Woodlice {Cmatacea Isopoda Terrestria) of Ulster. ' Proc Belfast N. 

F. C m., App. No. 3, 21-30. 1918. 

Gilchrlst, Dr. J. D. F. Note on Protective Resemblance, etc, in Post-larval 
Stages of some Cape Fishes. ' Trans. Royal Soc. South Africa,' vi. 205-208. 1917. 

Greaves, W. Bird Notes from Hebden Bridge. ' The Naturalist ' for 1917, 247- 
248. 

Vertebrate Zoology in Yorkshire. ' The Naturalist ' for 1918, 139-140. 

II 9. 



96 REPORTS ON THE STATE OF SCIENCE. — 1918. 

Geeer, Thomas. Lepidoptera from East Tyrone. ' Irish Naturalist,' ii. 4-6. 1918, 
Haggart, D. a. Botanical and other Notes : Mid Perth. ' Trans. Perthshire Soc. 

Nat. Sci.' VI. 169-182. 1917. 
Hallett, H. M. The Hemiptera of Glamorgan. 'Trans. C'ardifi Nat. See.' XLix. 

52-63. 1917. 

Entomological Notes, 1916. 'Trans. Cardiff Nat. Soc' xLix. 64-66. 1917. 

Hammond, L. F. Notes on Malacosoma neustria from Anzac Cove. ' Trans. Croydon 

N. H. Sci. Soc.' VIII. 133-135. 1917. 
Habgreaves, J. A., and .J. Digby Firth. Alien MoUusca in Yorkshire. ' The 

Naturalist ' for 1918, 125-126. 
Harrison^, J. W. He.slop. The Geographical Distribution of the Moths of the Sulx- 

Family Bistoninse. ' The Naturalist ' for 1917, 252-257, 293-296, 312-320 ; 

for 1918, 68-72, 155-157. 
Harvey, William. Plumatella Repens. Story of a Statoblast and what became 

of it. 'Trans. Manchester Mic. Soc' 1916, 87-91. 1918. 
Hastings, Somerville, and J. C. Mottram. Observations upon the Edibility of 

Fungi for Rodents. ' Trans. British Mycological Soc' v. 364-378. 1917. 
Heath, Alice. Bugula (the Bird's Head Zoophyte). ' Joum. Torquay N. H. Soc' 

n. 227-229. 1918. 
Hewitt, John. A Survey of the Scorpion Fauna of South Africa. ' Trans. Royal 

Soc. South Africa,' vi. 89-192. 1918. 
HoPKiNSON, John. Rotifers living in Rhizopods' Tests. ' Trans. Herts. N. H. 

S. F. C XVI. 269-272. 1917. 
Jackson, J. Wilfrid. Limncea glabra in Ireland ? With Note by R. A. Phillips. 

' Irish Naturalist,' xxvii. 77-79. 1918. 
John, Dr. A. H. Microscopical Report. Tran.s. N. Staffs. F. C. li. 115-117. 1917. 
Johnson, Lieut. Gilbert. Nature Notes from France. ' Trans. Caradoc and 

Severn Valley Field Club,' vi. 177-181. 1917. 
Johnson, Rev. W. F. Aculeate Hymenoptcra from the Counties of Armagh and 

Donegal. ' Irish Naturalist,' xxvii. 2-3. 1918. 
JouRDAiN, Francis C. R. Ornithological Report, 1915-17. ' Report Ashmolean 

Nat. Hist. Soc' 1917, 13-15. 1918. 
KiRKPATRicK, T. W. Report of the Diptera Section. 'Report Marlb. Coll. N. H. 

Soc' No. 66, 37-39. 1918. 
Langham, Sir Charles. Entomological Notes. ' Irish Naturalist,' xxvi. 114-117. 

1917. 
LoNES, Dr. T. E. Rotifers of the Countiy of the Chess and Gadc. Part ii. 'Trans. 

Herts. N. H. S. F. C xvl 221-236. "1917. 
Masefield, J. R. B. Zoological Report. ' Trans. N. Staffs. F. C.' li. 99-105. 1917. 
Maxwell, Sir Herbert. Animal Intelligence. ' Trans. Dumfriesshire and Galloway 

N. H. A. Soc' V. (Third Series), 10-33. 1918. 
Moffat, C. B. An Extermuiating Winter; its Effects on Bird-life in Co. Wexford. 

' Irish Naturalist,' xxvi. 89-98. 1917. 

Some Migrant Notes. ' Irish Naturalist,' xxvl 131-133. 1917. 

MoRLEY, B. Yorkshire Entomology in 1917. 'The Naturalist' for 1918, 97-98. 
Murray, Jas. Hemiptera Heteroptera of West Cumberland. ' The Naturalist ' for 

1918, 27-28. 
Newman, L. W. Notes on Rearmg Maaothylacia [Bonibyx) rubi. ' Proc. South 

London Ent. N. H. Soc' 1917-18, 6-7. 19i8. 
Oldham, Charles. Pisidium parvuhim in Hertfordshire. ' Trans. Herts. N. H. 

S. F. C xvn. 33-34. 1918. 
Openshaw, a. E. Notes on the Reproduction of Hydra. ' Trans. Manchester Mic. 

Soc' 1916, 46-49. 1918. 
Paynter, Henry A. Wild Birds of Hulne or Alnwick Park. ' History Berwickshire 

Nat. Club,' xxm. 409-410. 1918. 
Perkins, Dr. R. C. L. Notes on CalUmorpha dominula and Vespa austriaca. ' Joum. 

Torquay N. H. Soc' n. 142-145. 1918. 

On Parasitic (or Cuckoo) Bees and Wasps, ' Journ. Torquay N. H. Soc' 

n. 214-220. 1918. 

Phillips, R. A., and A. W. Stelfox. Recent Extensions of the Range of Pisidhim 

hibernimm. ' Irish Naturalist,' xxvii. 33-50. 1918. 
Pitt, Miss F. The Polecat. ' Trans. Caradoc and Severn Valley Field Club,' vi. 

105-120. 1917. 



CORRESPONDING SOCIETIES. 97 

I'EAEGER, R. Llovd. Irish Fossil Mollusks. ' Irish Naturalist,' xxvii. 09-74. I9I8. 
Proger, T. W., and D. R. Patekson. Ornithological Notes for 1916 'Trans 

Cardiff Nat. Soc' XLix. 67-09. 1917. 
Prout, L. Some Points of Interest in the Geomctridse. ' Trans. London N H 

Soc' 1914, 41-48. 1917. 
Reid, R. C, and Mrs. G. W. Shirley. Two Ornithological Notes : Plutyctrcus 

Eximus ; Terdus Mcru'.a. ' Trans. Dumfriesshire and Galloway N. H. A Soc ' v 

(Third Series), 230-231. 1918. 
Richardson, Nelson M. Anniversary' Address. ' Proc. Dorset N. H A F C ' 

xxxvra. 1-22. 1918. 
RoussELET, C. F. Some Further Notes on Collecting and Mounting Rotifera 

' Journ. Quekett Mie. Club,' xm. 321-328. 1917. 
RuTTLEDGE, ROBERT F. Omitliological Notes from South Mayo. ' Irish Naturalist ' 

XXVI. 148-151. 1917. 
ScH.ARFF, R. F. Advances in Irish Marine Zoologj-. Fourth Report ' Irish 

Naturalist,' xxvi. 103-113. 1917. 

On the Irish Pig. ' Irish Naturalist,' xxvi. 173-185. 1917. 

SCHLESCH, Hans. Notes on Planorbis and Margaritana in Iceland. ' The Naturalist ' 

for 1917, 201. 
Dreissensia polymorpha, Pallas. ' The Naturalist ' for 1917, 234. 

The Icelandic Forms of Limnma. ' The Naturalist ' for 1917, 257-259. 

Notes on the Slugs and Land Shells of Iceland.' ' The Naturalist ' for 1917 

297-300, 330-332. 

Notes on Margaritana margaritifera (Linne). ' The Naturalist' for 1917, 332- 

oo-±. 

Selous, Edmund. Ornithological Observations and Reflections in Shetland 'The 

Naturalist ' for 1917, 260-269 ; 1918, 131-135, 158-160. 
SiMES, J. A. Aspects of Bird-life in Europe. ' Trans. London N. H. Soc ' 1916 

77-89. 1917. 
Soar, Charles D. The Water Mites (Hydracarina) of Epping Forest ' Essex 

Naturalist,' xvni. 96-105. 1917. 
Stainforth, T. The Woodlice of the Hull District. 'The Naturalist' for 1918 

151-154. 
Stowell, E. a. C. Report of the Entomological Section. ' Report Marlb Coll 

N. H. Soc.' No. 66, 30-36. 1918. 
Stubbs, Fredk. .J. On a Blue Egg of the Lapwing. ' Essex Naturalist,' xvin 

105-106. 1917. 

Notes on certain Breeding Habits of the Snipe. ' Essex Naturalist,' xvui. 

109-110. 1917. 

■ The Corncrake in Essex. ' Essex Naturalist,' xviii. 189-192. 1918. 

The London Gulls. ' Trans. London N. H. Soc' 1916,37-41. 1917. 



Talbot, Geoffrey. Pathogenic Protozoa. ' Trans. Manchester Mic Soc ' 1916, 

66-86. 1918. 
Tayxor, J. W. Helix cartusiana and Helix syriaca : their Relationship and its 

Probable Significance. ' The Naturalist ' for 1918, 25-26. 
Remarks upon 'The Post-Pliocene Non-Marine Mollusca of Ireland.' The 

Naturalist ' for 1918, 161-1G5. 
Upton, Charles. Additional Notes on the Land and Freshwater Mollusca of 

Gloucestershire. ' Proc. Cotteswold N. F. C xix. 229-232. 1918. 
Watkin, Hugh R. Why the Nightingale is seldom heard in Devon. 'Journ. 

Torquay N. H. Soc' ri. 236-237. 1918. 
Williamson, W., and Charles D. Soar. Lehertia sefvei Walter. 'Journ. Quekett 

Mic. Club,' XIII. 375-378. 1918. 
Woodruffe-Peacock, Rev. E. Adrian, and Thomas Warner Woodruffe-Peacock. 

Thrush Stone Studies. ' Trans. Lincolnshire Nat. Union, 1916,' 54-59. 1917. 

Section E. — Geography. 

Campbell, John. Three Daj's in Snowdonia. ' Trans. Worcestershire Nat. Club,' 

VI. 222-231. 1917. 
Gass, John B. Greece and some of the Islands in the iEgean Sea. ' Journ. 

Manchester Geog. Soc' xxxm. 31-38. 1918. 



98 REPORTS ON THE STATE OF SCIENCE. — 1918. 

HuNTBACH, A. The Course of the River Sow. ' Trans. N. Staffs. F. C Li. 55-59. 

1917. 
Smith, Prof. G. Elliot. Ancient Mariners. ' Proc. Belfast N. H. Phil. Soc.' 1916- 

1917, 44-72. 1918. ' Journ. Manchester Geog. Soc. xxxra. 1-22. 1918. 
South-eastern Union of Scientific Societies. Report of the Regional Survey 

Committee, 1916-7. ' South-Eastem Naturalist ' for 1917, xxxm.-xsxvn. 1917. 
Thompson, Beeby. The River System of Northamptonshire. ' Journ. Northants 

N. H. Soc' XIX. 39-48, 55-70, 83-93. 1917. 
Wallace, Robert. The Lower Nith in its relation to Flooding and Navigation. 

' Trans. Dumfriesshire and Galloway N. H. A. Soc' v. (Third Series), 128-136. 

1918. 
WooDHOUSB, J. Carbon from the Geographical Standpoint. ' Proc. Bournemouth 

Nat. Sci. Soc' viii. 101-108. 1917. 

Section F. — Economic Science and Statistics. 

Batty, Robert B. State Purchase of the Liquor Trade. ' Trans. Manchester Stat. 

Soc' 1916-17, 35-56. 1917. 
Bradley, Edward J. The Severn : as it was, as it is, and as it should be. ' Trans. 

Worcestershire Nat. Club,' vi. 237-245. 1917. 
Casmey, W. H. (Manchester Geol. Min. Soc.) Coal Economy from a National 

Standpoint. ' Trans. Inst. Min. Eng.' Lv. 30-42. 1918. 
Ellinger, Barnard. The Case for a Guild of Shippers,with some Suggestions. ' Trans. 

Manchester Stat. Soc' 1916-17, 80-96. 1917. 
GouLTY, Howard. The Quantity Theory, with some reference to Bank Reserves. 

' Trans. Manchester Stat. Soc' 1916-17, 17-33. 1917. 
KiRKALDY, Prof . A. W. Economics after the War. 'Trans. Manchester Stat. Soc' 

1916-17, 1-15. 1917. 
McClelland, Prof. J. A. Scientific and Industrial Research. ' Proc. Belfast N. 

H. Phil. Soc' 1916-1917, 31-43. 1918. 
McDix, E. R. History of Early Piinting in Ireland. ' Proc. Belfast N. H. Phil. Soc* 

1916-1917, 5-29. 1918. 
Mo WAT, D. M. (Mining Inst. Scot.) Capital Charges considered along with Current 

Expenses. ' Trans. Inst. Min. Eng.' Liv. 317-320. 1918. 
Trueman, a. E. The Lias Brickyards of South-West Lincolnshire. ' Trans. Lincoln- 
shire Nat. Union,' 1916, 48-53. 1917. 

Section G. — Engineering. 

Booth, Fred. L. (N. England Inst. Eng.) The Strength of Pit-props. 'Trans. 

Inst. Min. Eng.' lv. 87-91. 1918. 
Crankshaw, Hugh M. (Manchester Geol. Min. Soc) Methods of Mining in the 

Pennsylvania Anthracite Field. 'Trans. Inst. Min. Eng.' liv. 113-133. 1917. 
DixoN, H. O. (Manchester Geol. Min. Soc.) The Thin Mine Problem. 'Trans. 

Inst. Min. Eng.' liv. 135-138. 1917. 
GiBB, George. (Min. Inst. Scotland.) A Fresh Aspect of Intensive Mining, Thin 

Seams. ' Trans. Inst. Min. Eng.' liv. 28-32. 1917. 
Jenkins, Harold C. (Midland Inst. Eng.) Underground Conveyers. ' Trans. 

Inst. Min. Eng.' LV. 2-19. 1918. 
Marriott, W. (Midland Counties Inst. Eng.) A New System of Reinforcement 

and some Uses of Concrete and Cement in Mining. ' Trans. Inst. Min. Eng.' 

LIV. 263-268. 1918. 
Maurice, William. Acetylene Mine Lamps. ' Trans. Inst. Min. Eng.' Lin. 227- 

252. 1917. 
MoRisoN, John. (N. England Inst. Eng.) A System of Storing and FilUng Small 

Coal, with Remarks upon the Prevention of Spontaneous Heating in Coal-heaps. 

' Trans. Inst. Min. Eng.' lv. 76-79. 1918. 
Poole, G. G. T. (N. England Inst. Eng.) Notes on the Uniflow Steam Engine. 

' Trans. Inst. Min. Eng.' liv. 339-355. 1918. 
Ravenshaw, H. W. (Midland Inst. Eng.) Some Useful Instniments for Colliery 

Power Plants. ' Trans. Inst. Min. Eng.' lv. 99-109. 1918. 



CORRESPONDING SOCIETIES. 99 

Ripper, Dr. William. (Midland Inst. Eng.) University Education in relation 
to Mining Engineering. ' Trans. Inst. Min. Eng.' Liv 287-291 1918 

Rowan Henry. (Min. Inst Scotland.) Stripping and Relining a Shaftat Cowden- 
beath, Fife. Trans. Inst. Mm. Eng.' lv. 56-60 1918 

Thompson J. G. (Manchester Geol. Min. Inst.) The ' Bold ' Timber-tram. ' Trans 
Inst. Mm. Eng.' lv. 156-157. 1918. ^'-h^. 

Section H. — Antheopology. 

Alsop, J. C. Anthropometrical Report. ' Report Marlb. Coll. N. H Soc ' No 66 
69-84. 1918. ■ ' 

Bury, Henry. Some ' Flat-faced ' Palseoliths from Famham. ' Proc. Preliistoric 

Soc. East AngUa,' n. 365-374. 1917. 
Chai^dleRj H. R. Some supposed Gun Flint Sites. ' Proc. Prehistoric Soc East 

Anglia, n. 360-365. 1917. 
Clarke, W.G. Are Grime's Graves Neolithic ? ' Proc. Prehistoric Soc. East Anglia,' 

-.and H. H. Halls. A' Cissbury Type 'Station at Great Melton. ' Proc Pre. 

historic Soc. East Anglia,' n. 374-380. 1917. 
Co AjTES, Henry. Note on Stone Cists found at Flawcraig and Bumf oot. 'Trans 

Perthshire Soc. Nat. Sci.' vi. 149-150. 1917. 
George, T. G. Early Man in Northamptonshire, with particular reference to the late 

Celtic Period as illustrated by Hunsbury Camp. ' Journ. Northants N. H. Soc ' 

XIX. 29-38. 1917. 
Kendall, Rev. H. G. O. Chipped Flints from below the Boulder Clay at Hertford 

Proc. Prehistoric Soc. East Anglia,' n. 352-359. 1917. 
Lawlor, H. C. Prehistoric Dwelling-places. (Second Paper.) ' Proc. Belfast N 

H. Phil. Soc. 1916-1917, 77-103. 1918. 
Lowe, Harford J. The Dartmoor Antiquities and their Builders. ' Journ. Torquay 

N. H. Soc II. 131-141. 1918. ^ 

Martin, Edward A. Skulls and Jaws of Ancient Man, and his Implements. 'South- 

Eastern Naturalist for 1917, 23-37. 1917. 
Mom, J. Reid 'The Position of Prehistoric Research in England. ' Proc. Prehistoric 

Soc. East Angha,' n. 381-391. 1917. 
Peake, Dr^ A. E. Presidential Address. Further Excavations at Grime's Graves. 
Proc. Prehistoric Soc. East Anglia,' ii. 409-436. 1917. 

A Prehistoric Site at Kimble, S. Bucks. ' Proc. Prehistoric Soc. East Anglia,* 

n. 437-458. 1918. "^ 

Sheppard, T. A Rare Type of Bronze-Age Weapon from Lincolnshire. 'The 
Naturahst for 1917, 281. 1917. 

More Bronze-Age Relics from Scarborough. ' The Naturahst ' for 1917, 281 -284. 

7qi o Ko'^i'^*^ ^^ *^® Bronze Age in the Whitby Museum. ' The Naturalist ' for 

lyiOj Oi?— ox. 

Turner, Hy. J. Annual Address : Some possible Steps in the Evolution of Man. 
Proc. South London Ent. N. H. Soc' 1917-18, 13-21. 1918. 

Section I. — Physiology. 

Haldane, Dr. J. S. Abnormal Atmospheres and the Means of Defence against them. 

South-Eastem Naturalist ' for 1917, 70-85. 1917. 
Jolly, W. A. The Electro-motive Changes accompanying Activity in the Mammalian 

Ureter. ' Trans. Royal Soc. South Africa,' vi. 227-230. 1917. 
MacBride, Prof. E. W. Are Acquired Character inherited ? ' South-Eastem 

Naturalist ' for 1917, 38-52. 1917. 
Talbot, Geoffrey. Pathogenic Protozoa. 'Trans. Manchester Mic. Soc' 1916, 

66-86. 1918. 
Wallis, Eustace F. Mosquitos and Malaria. ' .Journ. Northants N. H. Soc ' xix 

71-73. 1917. 

Section K. — Botany. 

Arnott, Provost S. Characteristics of Alpine Plants. 'Trans. Dumfriesshire 
and Galloway N. H. A. Soc' v. (Third Series), 110-114. 1918. 

Bayford, E. G. (Annotated by F. A. Lees.) A Floral Film of 1831. ' The NaturaUst ' 
for 1918, 89-92. 



loo REPORTS ON THE STATE OF SCIENCE. — 19] S. 

BouLGER, G. S. The Association of the Chelsea Physic Garden with the History of 

Botany. ' South-Eastern Naturalist ' for 1917, 86-96. 1917. 
Bbierley, C. H. Plaiit Hairs. ' Journ. Manchester Mic. Soc' 1916, 55-61. 1918. 
BuLLEK, Prof. A. H. Reginald. Some Critical Remarks on the Generic Positions 

of Psathyra vrticaecola Berk, et Broome, Coprinus plicatilis Fr., and Psathyrella 

disseminata Pers. ' Trans. British Mycological Soc' v. 482-489. 1917. 
BuTTERFiELD, E. P. Romance of the Cuckoo. ' The Naturalist ' for 1918, 93-96, 

127-130. 
Caradoc and Severn Valley Field Club. Botanical Notes. ' Record of Bare 

Facts ' No. 26, 5-12. 1917. 
Chadwick, J. A. Report of tlie Botanical Section. ' Report Marlb. Coll. N. H. 

Soc' No. 66, 21-29. 1918. 
CheeSMAN, W. N. Economic Mycology : The Beneficial and Injurious Influences 

of Fungi. (Presidential Address to the Yorkshire Naturalists' Union.) 'The 

Naturalist ' for 1917, 185-200. 
Colgan, Nathaniel. Notes on Apparent Mnemic Action in Cldora perfoliaia. 

' Irish NaturaUst,' xxvi. 189-193. 1917. 
' Lusitania and Kerry : A Botanical Parallel. ' Irish Naturalist,' xxvii. 20-26 . 

1918. 
€uRTis, W. Parkinson. Phonological Report on First Appearances of Birds, 

Insects, (fee, and First Flowering of Plants in Dorset for 1916. ' Proc. Dorset 

N. H. A. F. C xxx\Tii. 133-232. 1918. 
Druce. G. Claridge. Ewelme Plants, recorded from 1796 to 1799 by John Randolph, 

Bishop of Oxford. ' Report Ashmolean Nat. Hist. Soc' 1917, 23-42. 1918. 
DuTHiE, A. V. On Hybrid Forms in the Genus Satyrum, with Descriptions of Two 

Now Forms. ' Trans. Royal Soc. South Africa,' vi. 289-294. 1917. 

African My.xomycetes, ' Trans. Royal Soc. South Africa.' vi. 297-310. 1917. 

Elliott, Dr. Jessie S.BAYLIS.S. Studies in Discomycetcs. I. ' Trans. British Myco- 
logical Soc." V. 417-421. 1917. 
Elliott, Dr. W. T. Some Observations upon the Assimilation of Fungi by Badhamia 

lUricidaris Berk. ' Trans. British Mycological Soc' v. 410-413. 1917. 
Falconer, Wm. Plant Galls of the Huddersfield District. ' The Naturalist ' for 

1918, 166-168. 
•GooDE, G. H. Additional List of Plants to those on p. 231, vol. xvm., December, 

1916. ' Jouni. Northants N. H. Soc' xix. 50. 1917. 
Groves, J., and Canon G. R. Bullock Webster. Toli/pella nidifica, Leonh. 

' Irish Naturalist,' xxvi. 134-135. 1917. 
Haggart, D. a. Botanical and other Notes. ' Trans. Perthshire Soc. Nat. Sci.' 

VI. 169-182. 1917. 
Harris. G. T. On Schistosfega osmundacea Mohr. ' Journ. Quekett Mic. Club, 

XIII. 361-374. 1918. 
Harrison, P. Walton. Sensitive Plants. ' Selbornc Mag.' xxvrn. 130-131. 1917. 
Heinig, R. L. Root Suckers of the Ganges Delta. ' Journ. Torquay N. H. Soc' 

II. 158-162. 1918. 

The Melocanna Bamboo. ' Journ. Torquay N. H. Soc' ii. 221-225. 1918 

Henslow, Rev. Prof.C4. The Uses of Carbon in Plants. 'Proc Bournemouth Nat. 

Sci. Soc' vm. 95-101. 1917. 
HoPKiNSON, John. Report on the Phenological Observations in Hertfordshire 

for the year 1916. ' Trans. Herts N. H. S. F. C xvn. 47-52. 1918. 
Ingham, Wm. Sphagna. ' The Naturalist ' for 1917, 349-352, 392-397. 
J.iCKSON, Dr. B. Daydon. Notable Trees and Old Gardens of Londoa ' South- 

Eastern Naturalist ' for 1917, 58-69. 1917. 
Jbffery, F. Ronald. The Wyre Forest Sorb Tree {Pyrus domesHca). ' Trans. 

Worcestershire Nat. Club,' vi. 250-257. 1917. 
Johnson, Marie E. M. A Note on Two interesting Fungi : Botrytis pyramidalis 

Sacc. and Sphceioncema cornutwm Pr. ' Trans. British Mycological Soc' v. 

414-416. 1917. 
•Johnson, Rev. W. An Addition to the British Lichen Flora. ' The Naturalist ' for 

1918, 103. 
Jones, D. A. The Mosses and Hepatics of Denbighshire. ' The Naturalist ' for 1917; 

285-292, 321-327. 



CORRESPONDING SOCIETIES. lOl 

Lees, F. Arnold. Hedge Beadstiaw among Stone Walls. ' Tlie Naturalist ' for 
1917, 328-329. 

The Colonist-Alien Heron-Bills of Yorkshire. ' The Naturalist ' for 1917, 379- 

386. 

LiSTEE, Miss GuLiELM.4.. A Short History of the Study of Mycetozoa in Britain, 
with a List of Species recorded from Essex. Presidential Address. ' Essex 
Naturalist,' xvm. 207-. 1918. 

Main, Hugh. Eiitonophthoia Americana : An American Fungus new to Europe. 
'Essex Naturalist,' xvm. 107-108. 1917. 

M.\YFIELD, A. The Lichens of a Bouldor-Clay Area. ' Joum. Ipswich F. C v. 
34-40. 1917. 

Moffat. C. B. Losses to a Local Flora. 'Irish NaturalLst," xxvi. 157-160. 1917. 

Morris, Sir Daniel. Presidential Address : Hardy British Trees. ' Proc. Bourne- 
mouth Nat. Sci. Soc' vm. 33-58. 1917. 

Paulson, Robert. The Varenne Collection of Lichens : A Report on its present 
condition. [1915.] ' Essex Naturalist,' xviii. 133-134. 1917. 

Peacock, H. G. Fungi, Lichens, and Mycetozoa. ' Joum. Torquay N. H. Soc.' ii. 
146-152. 1918, 

Pe.\.rson, Dr. H. H. W., and Mary R. H. Thomson. On some Stages in the Life 
History of Gnetum. ' Trans. Royal Soc. South Africa,' vi. 231-269. 1917. 

Pe.\rson, Wm. Hy. Hepaties of Denbighshire. ' The Naturalist ' for 1918, 60-67. 

Hepaties of the Hebden Bridge Valley. ' The Naturalist ' for 1918, 123-124. 

Pickard, Joseph Fry. Notes on the Flora of Ribble-Craven. ' The Naturalist ' 

for 1917, 347-348. 
Praeger, R. Lloyd. Equisetum littorah in Ireland. ' Irish Naturalist,' xxvi. 

141-147. 1917. 
Pugh, E. C. Tree Flowers. ' School Nature Study,' 12, 21-24. 1918. 
Ramsbottom, J. Training in Plant Patliology. ' Trans. British Mycological Soc.' 

V. 378-380. 1917. 

Recent published Results on the Cytology of Fungus Reproduction (1916). 

'Trans. British Mycological Soc' v. 441-461. 1917. 

Rawson, Col. H. E. Some Novel Experiments illustrating the Response of Plants 

to Selective Screening. 'Trans. Herts. N. H. S. F. C xvi. 259-268. 1917. 
Rea, Carleton. Report of the New Forest Foray (Sept. 1916) and Complete List 

of the Fungi and Mycetozoa. ' Trans. British Mycological Soc' v. 351-364. 1917. 
New or Rare British Fungi. ' Trans. British Mycological Soc' v. 434-440. 

1917. 
Rendle, Dr. A. B. President's Address : The Use of Microscopical Characters in 

the Systematic Study of the Higher Plants. ' Journ. Quekett Mic. Club.' xiii. 

353-360. 1918. 
Riddelsdell, Rev. J. H. Rtibus in Gloucestershire. ' Proc Cotteswold N. F. C. ' 

XIX. 213-227. 1918. 
Ridge, W. T. Boydon. Botanical Report. ' Trans. N. Staffs. F. C li. 107-113. 

1917. 
Rooper, Mlss C. Agnes. Report of the Botanical Section, including a Report on 

Spaitina Grass and a List of Rare or Uncommon British Plants for the District. 

' Proc. Bournemouth Nat. Sci. Soc' vni. 63-65. 1917. 
Roper, Miss Ida M. Presidential Address : Mistletoe. ' Proc Bristol Nat. Soc' 

VL (Ser. 4), 175-185. 1918. 
Ross, Joseph. Ptilidiiim pulcherrimum (Web), Hampe, in Epping Forest. ' Essex 

Naturalist,' xvm. 187-189. 1918. 
Mycetozoa in the Chingf ord District of Epping Forest in August and September, 

1915 and 1916. ' Essex Naturalist,' xvm. 192-193. 1918. 
S-ALISBURY, Dr. E. J. New Records of Hertfordshire Liverworts. ' Trans. Herts. 

N. H. S. F. C xvL 273-275. 1917. 

Botanical Observations in Hertfordshire during the j-ear 1916. ' Proc Herts. 

N. H. S. F. C xviL 13-15. 1918. 

The Ecology of Scrub in Hertfordshire : A Study m Colonisation. ' Trans. 

Herts. N. H. S. F. C xvii. 52-64. 1918. 

Sanderson, A. R. Mycetozoa of the Austwiek District. ' The Naturalist ' for 1918, 
62-65. 



102 REPORTS ON THE STATE OF SCIENCE. — 1918. 

Scott, D. H. (Midland Inst. Eng.) The Forests of the Coal Age. 'Trans. Inst. 

Min. Eng.' uv. 33^9. 1917. 
Shadbolt, L. p. The American Poison- Vine Rhus toxicodendron at Bushey. ' Trans. 

Herts. N. H. S. F. C xvn. 1-4. 1918. 
Smith, A. Loebain, and J. Ramsbottom. New or Rare Miorof ungi. ' Trans. British 

Mycological Soc' v. 422-433. 1917. 
South-Eastern Union op Scientific Societies. Report of the Botanical Section, 

including that of the Cryptogamic Committee. ' South-Eastem Naturalist ' 

for 1917, xm.-xxn. 1917. 
SwANTON, E. W. Presidential Address : Education in Mycology. ' Trans. British 

Mycological Soc' v. 381-407. 1917. 

Economic and Folk Lore Notes. ' Trans. British Mycological Soc' v. 408^09. 

1917. 

Tench, Samuel Edward. The Strangling Fig. ' Selbome Mag.' xxvm. 121-124. 

1917. 
Van der Bijl, Paul A. Note on Poli/saccum crassipea, D. C, a Common Fungus 

in Eucalyptus Plantations round Pretoria. ' Trans. Royal Soc. South Africa,' vi. 

209-214. 1917. 

Heart Rot of Ptmroxylon utile (Sneezewood) caused by Fames rimosvs (Berk.) 

' Trans. Royal Soc. South Africa,' vi. 215-226. 1917. 

Wakefield, E. M. Notes on British Thelephoracese. ' Trans. British Mycological 

Soc' V. 474-481. 1917. 
Weiss, Prof. F. E. Presidential Address : Seeds and Seedlings of Orchids. ' Trans. 

Manchester Mic Soc' 1916, 32-43. 1918. 
White, Jas. W. Bristol Botany in 1915 and 1916. ' Proc. Bristol Nat. Soc' iv. 

(Ser. 4), 198-203. 1918. 
Wilkinson, Henry J. Catalogue of British Plants in the Herbarium of the York- 
shire Philosophical Society. Part xi. ' Report Yorkshire Phil. Soc. for 1916,' 

11-172. 1917. 
Willis, H. G. Notes on Two Hepatics. ' Trans. Manchester Mic. Soc' 1916, 44^45. 

1918. 
Wilson, Miss I. Crae Lane and its Vegetation. ' Trans. Dumfriesshire and 

Galloway N. H. A. Soc' v. (Third Series). 124-126. 1918. 
Woodruffe-Peacock, Rev. E. Adrian. Presidential Address. The Flora of 

Lincolnshire ; Sequence-Selections. ' Trans. Lincolnshire Nat. Union, 1916,' 

22-40. 1917. 

Section L. — Education. 

Jabvie, W. (Min. Inst. Scotland). Notes on the Education (Scotland) Bill. ' Trans. 

Inst. Min. Eng.' lv. 149-154. 1918. 
Kerr, G. L. (Min. Inst. Scotland.) The Higher Training of Colliery Managers. 

' Trans. Inst. Min. Eng.' Lm. 182-192. 1917. 
Pickup, William (Manchester Geol. Min. Soc). Presidential Address. Mining 

Education and Research in Lancaslme : An Appeal for Wider Interest and Greater 

Support. ' Trans. Inst. Min. Eng.' Liv. 275-285. 1918. 
Welldon, Bishop. Education after the War. ' Trans. Manchester Stat. Soc. 

1916-17,' 57-78. 1917. 

Section M. — Agriculture. 

Donald, J. A. Some Aspects of the Forestry Question. ' Trans. Perthshire Soc. 
Nat. Sci.' VL 159-168. 1917. 

Obituaries. 

Beaithwjvite, Dr. Robert. ' Journ. Quekett Mic. Club,' xm. 350-351. 1917. 
Cooper, Wilfrid Omee, By W. M. R. ' Proc. Bournemouth Nat. Sci. Soc' vin. 

71-72. 1917. 
Crake, William Vandeleur. By A. B. 'Hastings and East Sussex Naturalist,' 

n. 254-255. 1917. 
Crossland, Charles. By J. Ramsbottom. ' Trans. British Mycological Soc' 

V. 466-469. 1917. 



CORKESPONDING SOCIETIES. 103 

Dawsox, Charles. ' Hastings and East Sussex Naturalist,' ii. 251-253. 1917. 
Ellis, John William. Bv J. Kamsbottom. ' Trans. British Mycological Soc' v. 

462-464. 1917. 
Geeenwell, Canon William. Bv T. S[heppaid]. ' The Naturalist ' for 1918, 

104-106. 1918. 
Hawkiks, John. By S. C. S. and E. A. W. P. ' Trans. Lincolnshire Nat. Union, 

1916,' 41-47. 1917. 
HowAjiTH, J. H. By T. S[heppard]. ' The Naturalist ' for 1918, 172-173. 
Hughes, Prof. T. McKenny. By T. S[heppard]. ' The NaturaUst ' for 1917, 

237-238. 
Hull, Dr. Edward. By I'lof. Grenville A. J. Cole. ' Irish Naturalist,' xxvji. 

17-19. 1918. 
Juli.4,n, Henry Forbes. By Mrs. Hester Forbes Julian. ' Joum. Torquay N. H. 

Soc.' n. 230-235. 1918. 
Latham, Baldwin. By F. Campbell-Bayard. ' Proc. Croydon N. H. Sci. Soc.' 

vni. xcvm.-ci. 1917. 
Lebour, Prof. G. A. L. By T. S[heppard]. 'The Naturalist ' for 1918, 106-107. 
Massee, George Edw.vrd. By J. Kamsbottom. 'Trans. British Mycological 

Soc.' V. 469-473. 1917. 
Meeiv.vle, John Herm.a.n. By Judith Merivale. 'Trans. Inst. Mm. Eng.' liv. 

364-366, 1918. 
Pickard-Cambridge, Rev. 0. By Arthur Wallace Pickard-Cambridge. ' Proc. 

Dorset N. H. A. F. C xxxvm. xli.-lii. 1918. 
Slater, Matthew B. Bv T. S[heppard]. ' The Naturalist * for 1918, 108-109. 
Turner, W. Barwell. By E,. ' The Naturalist ' for 1917, 202-205. 



3SEPJ919 




Section B.— 1918.] [British Association. 



Colloid Chemistry and its General and Industrial Applications. — 
Second Report of the Committee, consisting of Professor F. G. 
TfossAi^ {Chairman), Professor W. C. McC. Lewis (Secretary), 
Dr. E. F, Armstrong, Professor Adrian J. Brown, Dr. C. 
H. Desch, Mr. E. Hatschek, Professors H. R. Procter 
and W. Ramsden, Mr. A. S. Shorter, Dr. H. P. Stevens, 
and Mr. H. B. Stocks. 

Introduction. 

The plan already adopted of arranging the subject-matter under 
two heads, viz. (1), classification according to scientific subject, and 
(,2), classification according to industrial process and general applica- 
tion of colloid chemistry to other sciencbS, has been employed in the 
preparation of the Second Report. 

The subjects dealt with under the first head in the accompanying 
Report are : — 

1. Peptisation and Precipitation. 

2. Emulsions. 

3. The Liesegang Phenomenon. 

4. Electrical Endosmose, Part I. 

The subjects dealt with under the second head are : — 

1. Electrical Endosmose, Part II. 

2. Colloid Chemistry in the Textile Industries. 

3. Colloids in Agriculture. 

4. Sewage Purification. 

5. Dairy Chemistry. 

6. Colloid Chemistry in Physiology. 

7. Administration of Colloids in Disease. 

The Committee has again to express its deep sense of obligation to 
the gentlemen who under somewhat difficult circumstances have 
compiled the various sections which make up the present Report. 

It is hoped that the very valuable material which has now been 
collected in the First and Second Reports will serve the purpose of 
emphasising the fundamental importance of colloid chemistry for 
operations and processes which, at first sight, appear to be wholly 
distinct, and at the same time will serve to co-ordinate such informa- 
tion and to render it available for the benefit of all who are engaged 
in operations in which colloid chemistry plays a part. 

A number of subjects have not as yet been considered. It is 
hoped that these will be discussed in the Third Report. In this 
connection the Secretary {Muspratt Laboratory, University, 
Liverpool) would be glad of suggestions from those engaged in 
chemical industry regarding subjects or problems met with in 
technical work which could be considered as coming within the 
scope of the Committee's activities. It is felt that such co-operation, 
which at the present time would be particularly valuable, is not 
iinpossible. 

(20895.) \Vt. 36589—540. 2750. I/I9. D &; S. G. 2. A 



2 REPORTS ON THE STATE OF SCIENCE. 1918. 

REPORT ON PEPTISATION AND PRECIPITATION. 
By Professor Wilder D. Bancroft, Cornell University. 

Sufficiently small particles will be kept in suspension in a liquid 
by the Brownian movements. Any method which will form small 
particles and will keep them from coalescing will give rise to col- 
loidal solutions. Tentative theories of pejDtisation have been dis- 
cussed by Lottermoser/ Jordis,^ Mecklenburg,^ and von Weimarn.* 
If we adopt Freundlich's view^ that adsorption always lowers the 
surface tension, a theory of peptisation follows at once,^ because an 
adsorbed film with a low surface tension on the solvent side and a 
high one on the other side will tend to disintegrate or peptise the 
other substance as internal phase. 

When a liquid is adsorbed by a solid, it will tend to peptise it 
and in some cases will do so. Water peptises tannin readily and 
amyl acetate peptises pyroxylin. At higher temperatures the pep- 
tising action increases. Gelatine is peptised by warm and not by 
cold water. Glass is peptised by hot water'' and vulcanised rubber 
by various heated organic liquids,^ while fused baths peptise metals." 

There are a number of cases where mixed solvents v;ill peptise 
a solid much better than either one alone — celluloid nitrate in ether 
and alcohol, caseine in pyridine and water,^" and probably cinchonine 
in chloroform and alcohol," as well as phloretine in ether and water.'^ 
The theory of this has not been worked out. Cellulose nitrate swells 
in alcohol and not in ether ;i^ but it is not known whether this is 
universal or whether alcohol peptises cellulose nitrate at higher 
temperatures. Zein is also peptised in mixed solvents.^^ 

Relatively little work has been done on direct peptisation by 
means of a dissolved non-electrolyte, but a good deal of stress has 
been laid on the cases where a non-electrolyte prevents the formation 
of a visible precipitate. A concentrated solution of sugar in water 
will prevent the precipitation of calcium silicate,^^ silver chromate, 
and silver chloride •,^'' also of lime and of the hydrous oxides of 
copper,!'' uranium, and iron.'** Invert sugar is about seven times 
as effective as cane sugar in holding up hydrous ferric oxide. 

' Lottermoser, Jour. praM. Chem. (2) 68, 341 (1903) ; 72, 39 (1905) : 73, 374 
(1906); Zeit.phys. Chem. 62, 371 (1908). 
^ Jordis, Van. Bemmeli'n Gedenkboek, 215. 
» Zeit. anorg. Chem. 74, 260 .(1912). 

* Lehre von den Zustdnden der 3Iaterie, 1, 60 (1914). 

* Kapillarchemie, 52, 154 (1909); Patrick, Zeit.phys. Chem.. 86, 545 (1914). 
6 Bancroft, Jour. phyn. Chem. 70, 85 (1916). 

' BaruB, Am. Jour. Soi. (3) 41, 110 (1891); (4) 6, 270 (1898) ; 7, 1 (1899) ; Phil 
Mag. (5) 47. 104, 461 (1899). 

« Barus, Am. Jour. Soi. (3) 42, 359 (1891). 

' Lorenz, Van Bemmelen Gedenliboeh. 395. 

'" Levites, Zeit. Kolloidchemie, g, 4 (1911). 

" Oudemanns, J(wr. Chem. Soo. 26, 533 (1873). 

" Schiflf, Zeit.phys. Chem. 23, 355 (1897). 

'3 Private CommTinication from Professor Chamot. 

'■• Galeottoand Giampalmo, Zeit. Kolloidchemie, 3, 118 (1908). 

'5 Weisberg, Bull. Soc. Chem. Paris (3), 15. 1097 (1896). 

's Lobry de Bruyn, Ber. deutseh. Chevi. Oes. 35, 3079 (1902). 

•■ Graham, Jour. Chem. Soc. 15, 253 (1862). 

>8 RifEard, Comptes rendus, 77. 1103 (1873). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 3 

Grimauxi* showed that glycerine prevents the precipitation of 
hydrous ferric oxide by caustic potash. 

If one ion of an electrolyte is adsorbed more than the other ion, 
it will tend to peptise the adsorbing material and to give rise to a 
colloidal solution containing positively or negatively charged particles 
according to the nature of the adsorbed ion. Univalent ions are not 
all adsorbed alike ; nor are bivalent or trivalent ions. The order of 
adsorption is speciiic with each substance. Certain univalent ions 
are adsorbed by certain substances more than certain bivalent or 
trivalent ions.^" In many cases there is, however, a marked tendency 
to increased adsorption with increasing valence, as formulated in 
Schulze's so-called law.^^ It seems to be a general rule that insoluble 
electrolytes adsorb their own ions markedly. Consequently, a 
soluble salt having an ion in common with a sparingly soluble elec- 
trolyte will tend to peptise the latter. 

Freshly precipitated silver halides are peptised by dilute silver 
nitrate or the corresponding potassium halide,^^ the silver and the 
halide ions being adsorbed strongly. Many oxides are peptised by 
their chlorides or nitrates, forming so-called basic salts. -^ Sulphides 
are peptised by hydrogen sulphide.^"* Gelatine is liquefied or peptised 
by a potassiun iodide solution. The peptisation of hydrous oxides 
by caustic alkali can be considered as a case of common ion or as the 
preferential adsorption of hydroxyl ion.-^ Hydrous chromic oxide 
gives an apparently clear green solution when treated with an excess 
of caustic potash ; but the green oxide can be filtered out completely 
by means of a collodion filter, a colourless solution passing through.^^ 
Hantzsch^'' considers that hydrous beryllium oxide is peptised by 
caustic alkali, copper oxide is peptised by concentrated alkali,^^ and 
so is cobalt oxide.^^ In ammoniacal copper solutions part of the copper 
oxide is apparently colloidal and part is dissolved. ^'^ Freshly precipi- 
tated zinc hydroxide is peptised by alkali ; but the solution is very 
instable, the zinc hydroxide often coagulating inside of half an hour. 

The relatively small amount of zinc remaining in solution is 
present chiefly or entirely as sodium zincate.^^ The bulk of the 

•9 Comptes rendus, 98, U85, 1540 (1884). 

20 Bancroft, Jour. Phys. Chem. 19, 363 (1915). 

21 Schulze, Jour, prakt. Chem. (2), 25, 431 (1882) ; 27, 320 (1884). 

'2 Lottermoser, Jour. praM. Chem. (2) 60, 341 (1903); 72, 39(190.5); 73,374 
(1906) Zeit.phys. Chem. 62, 371 (1908). 

" Miiller, Ber. deutsch. chem. Ges. 39, 2856 (1906) ; Zeit. anorg. Chem. 52, 316 
(1907). Szilard, Jour. Chim. phys. 5, 488, 636 (1907). Graham, Jour. Chem. Soo. 
15, 254 (1862). 

2< Spring, Ber. deuUch. chem-. Ges. 16, 1142 (188,'«). Prost, Jour. Chem. Soc. 54, 
653 (1888). Winssing-er, Bull. Soc. chim. Paris (3) 49, 452 (1888). Linder and 
Picton, Jotir. Chem. Soc. 61, 116 (1892). Meunier, Comptes rendus, 124, 1151 (1897). 
Young, Jour. Phys. Chem. 21, 1, 14 (1917). 

^^ Bancroft, Jour. Phys. Chem. 20, -'9 (1916). 

'^ Fischer and Herz, Zeit. anorg. Chem. 31, 352 (1902). Fischer, Zeit. anorg. Chem. 
40, 39 (190 1). Nagel, Jour. Phys. Chem.. 19, 331, 569 (1915). 

■'1 Zeit. amrg. Chem. 30, 289 (1902). 

28 Loew, Zeit. anal. Chan. 8, 463 (1870). Fischer, Zeit. anorg: Chem. 40, 39 (1904). 

29 Tubandt, Zeit. anorg. Chem. 45, 368 (1905). 

3" Peligot, Ann. Chim.. Phys. (3) 63, 3*3 (1861). Guignet, Comptei rendus, 55, 
741 (1862). Grimaux, Comptes rendus, 98, 1434 (1884). 

" Hantzsch, Zeit. anorg. Chem. 30, 289 (1902) ; 75, 371 (1912) ; Fischer and Herz, 
Zeit. anorg. Chem. 31, 352 (1902) ; Klein, Zeit. anorg. Chem. 74, 157 (1912). 

30895 4 3 



4 REPORTS ON THE STATE OF SCIENCE. 1918. 

evidence seems to be that alumina is not peptised appreciably by 
alkali and that it goes into solution as sodium aluminate,^^ though 
the other view has been supported.^^ Adsorption of hydroxyl ion 
accounts for the peptisation of silicic acid^* and caseine by alkalies. 
Caseine can also be peptised by acids. A. Miiller^* has prepared 
colloidal solutions of aluminum, iron, cobalt, thorium, and yttrium 
oxides by peptisation with dilute hydrochloric acid, and Bentley and 
Rose^^ have peptised freshly precipitated alumina with 8 per cent, 
acetic acid. It is possible, but not probable, that the peptisation is 
done by a trace of metallic salt formed by the acid and not by the 
hydrogen ion. 

There are no cases where it has been shown conclusively that 
peptisation is due chiefly to adsorption of undissociated salt, but 
undoubtedly such instances'will be found. Water-peptisable colloids 
like gelatin,^^ gum arabic,^^ dextrine,^^ soap,'*'^ or saponine,*^ will 
peptise many precipitates, and they are often called protecting 
colloids, because they prevent the agglomeration and consequent 
settling of finely divided precipitates. Caseine is not peptised by water, 
but acts a protecting colloid when peptised by acids or alkalies; 
Hydrous chromic oxide when peptised by caustic potash can then 
prevent the precipitation of hydrous ferric oxide &c. If too much 
ferric oxide is present, all the chromic oxide is carried down by it.''^ 

Solutions of copper oxide in ammonia will peptise chromic oxide. 
*^Molybdic acid is not precipitated from its salts by uranyl salts, but 
tungstic acid is. In presence of tungstic acid, practically all the 
molybdic acid is precipitated. This is obviously a case of adsorption 
and the converse is undoubtedly true that no tungstic acid would 
be precipitated in presence of a sufficient excess of a molybdate.** 
Aniline dyes, which are insoluble in benzene, can be peptised by a 
benzene-soluble colloid such as the so-called zinc or magnesium 
resinate.** 

Since a colloidal solution is one in which a finely divided phase 
is kept from coalescing in some way, it is clear that there may be any 
number of colloidal aluminas, for instance, varying from anhydrous 

'» Herz, Zeit. anorg. Chem. 25, 155 (1900). Hantzsch, Zeit. anorg. Chem. 30, 289 
(1902). Rubenbauer, Zeit. anorg. Chem. 30, 331 (1902). Fischer and Herz, Zeit. 
anorg. Chem. 31, 355 (1902). Slade, Jour. Chem. Hoc. 93, 421 (1908) ; Zeit. anorg. 
Chem. 77, 457 (1912) ; Tram. Faraday Soo.. 10, 150 (1914). Blum, Jour. Am. 
Chem. Soc. 35, 1499 (1913). 

3' Mahin, Ingraham and Stewart, Jour. Avi. Chem. Soc. 35, 30 (1913). 

3< Graham, Jour. Chem. Sno. 17, 324 (1864). 

^^ Svedberg, Die Methoden zur Herstellung hoUoider Losungen anorganischer Stoffe, 
400 (1909). 

36 Jour. Am. Chem. Soc. 35, 1490 (1913). 

" Eder's Handhuch der PhntograjMe, 5th Ed. 3, I, 28 (1902). Luppo-Cramer. 
Phot. Correspondenz, 44, 578 (1907). 

'8 Lefort and Thibault, Jour. Chem. Soc. 42, 1322 (1882). 

39 Lachaud. Bull. Soc. diim. Paris (3) 15, 1105 (1896). 

« Spring, Zeit. Kolloidchemie 4, 161 (1909) ; 6, H. 109. 164 (1910). 

<' Schiaparelli, Jour. Chem. Soc. 46, 333 (1884). 

^2 Northcote and Church, Jour. Chem. Soc. 6, 54 (1854) ; Nagel, Jour. Phys. Chem. 
19, 331 (1915). 

« Prud'homme, Jour. Chem. Soc. 25, 672 (1872). 

" Miss Hitchcock, Jour. Am. Chem. Soc. 17, 483, 520 (1895) ; Wohler. Zei,t. Elektro- 
rhcmie, 16, 693 (1910). 

''•'' Soxhlet, Art of Dyeing and Staining Marble, Sfc. 76 (1902). 



Oi\ COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 

alumina (AI2O3) up to the most highly hydrous form that can be 
obtained. As a matter of fact, people have generally been satisfied 
with distinguishing only two sets of colloidal solutions, which they 
have called solutions of alumina and metalumina, stannic and 
metastaunic acids, &c.*® While adsorption will cause peptieation 
under suitable conditions, the disintegrating power of the adsorbed 
substance is relatively small and often is not sufficient to break up 
solid masses. A protecting colloid, for instance, will prevent the 
formation of a precipitate when it may not be able to disintegrate a 
massive precipitate. 

The preparation of colloidal solutions by peptisation is usually 
classed under the general head of dispersion methods. Five different 
tj'pes may be distinguished : — 

1. Removal of Agglomerating Agent. — If a precipitate has settled 
from a colloidal solution owing to the addition of too much of an 
agglomerating agent, the precipitate may go back into apparent 
solution if the excess of agglomerating agent is washed out. No 
colloidal solution will be obtained if it is impossible to wash oiit the 
coagulating agent or if the agglomeration has gone too far.'*^ If a 
silver halide precipitate is washed on a filter at once, the silver salt 
is apt to run through the filter when the excess of potassium s'llt has 
been removed and there is present only the amount which would 
have kept the silver halide in suspension originally. When the rare 
earth nitrates are precipitated by ammonia and then washed, they 
are liable to stay suspended in the liquid when the ammonium 
nitrate is nearly all removed. In alloy work stannic oxide should be 
washed with dilute nitric acid and not with water. Zinc sulphide 
is apt to forma colloidal sohition when the ammonium salt is washed 
out,^** and copper ferrocyanide does the same thing if all the copper 
sulphate is removed by washing-^^ In fact, Chautard^" claims that 
the quicl<est way to wash a gelatinous precipitate is to evaporate the 
solution to dryness and heat before trying to wash. Merely evapor- 
ating on a water-bath is not always sufficient." 

2. Addition of Peptising Agent. — Instead of washing out a pre- 
cipitating agent, a peptising agent may be added. Ammonia is very 
effective in suspending clay,''*^ silicic acid is peptised readily by 
caustic soda,^^ and Prussian blue is peptised by oxalic acid or by 
potassium oxalate. In some cases the concentration of the peptising 
agent has to be high, as when oxides are peptised by alkali, and 
people usually assume the formation of compounds. 

The action of soap on rouge or carbon black^^ looks like a disin- 
tegration ; but it is not. If a suspension of carbon black in water 

<6 Hantzsch, iTeii!. anonj. Chem.. 30, 338 (1902) ; Bancroft, Jour. Pliijg. Chem. 19, 
232 (1915). 

" Cf. Abegg and Schroeder, /elt. Kolhiidohemie, %, 85 (1907). 

« Donnini, Jour. Chem. Sor. 66 H. 318 (1894). 

« Berkeley and Hartley, Fh'd. Tram. 206 K 486 (1906). 

=" Jtmr. Chem. Soc. 26- ^27 (1873). 

5> Wright, Ihid. 43, J56 (1883) ; Kratz : .Tour. Phyx. Chem. 16, 121 (1912). 

■•5 Skcy. Chem. Nen^s, I7, Ifi-t (.1868) : 22, 236 (1870) ; 34, U2 (1876) ; see also 
Doelter, Handhuch dcr Mineralchemie^ 2- 122 (1912). 

^'3 Graham, .Tour. Chem. Sue. 17, 324 (1864). 

^* Spring, Zeit. KolUndchemie, 4, 161 (1909) ; 6, H, 109. 164 (1909). 
Bancroft, ,7y«v Phijs. Chem. 20, 107 (1916). 
20895 A 3 



6 REPORTS ON THE STATE OF SCIENCE. 1918. 

be filtered several times through filter-paper, the water will finally 
run through clear, and the carbon black will be held back by the 
filter-paper. If a soap solution be poured on the filter, a black filtrate 
is obtained and the filter-paper is no longer black. All the carbon 
black has passed through the filter paper. The same thing can be 
done with rouge, except that a red filtrate ie obtained instead of a 
black one. At first sight it seems that though the soap must have 
broken up the carbon or the rouge into finer particles, which then 
passed through the filter, but this is probably not so. The filter- 
paper is porous enough at first to let through the particles of carbon 
or rouge, as is shown by the fact that some of the suspended matter 
does pass through the filter at first. The cellulose adsorbs the carbon 
black or the rouge, and this clogs the filter to such an extent that the 
pores are not large enough to let the remaining particles through. 
The soap removes the rouge or the carbon black from the paper 
because it adsorbs these substances more strongly, and everything, 
therefore, goes through the paper. That this is the true explanation 
can be shown in two ways. In the first place, the experiment does 
not succeed if the rouge or the carbon is two coarse. In the second 
place. Spring showed that we are dealing with an adsorption of 
carbon black by filter-paper. If the black filter-paper be reversed 
and washed with water, the water removes only the black which is 
not in immediate contact with the paper. 

3. Mechanical Disintegration. — If a solid be ground sufficiently 
fine, it will necessarily form a colloidal solution for a time. This 
has been done experimentally by Wegelin^^ in the case of a number 
of metals. The addition of gelatin makes it easier to disintegrate 
ductile metals. Since a finely divided solid is more soluble, it is 
possible that it may go into solution and then precipitate in another 
form. This seems to happen with quartz. When reduced to an 
impalpable powder by long j^rinding, quarts can be converted into 
colloidal hydrous silicic acid merely by boiling with water.^^ 

4. Electrical Disintegration. — When a direct current arc is 
formed under water between two wires, the metal is disintegrated and 
colloidal solutions of platinum, iridium, palladium, gold, silver, and 
cadmium may be obtained in this way.^'' Satisfactory conditions are 
obtained with 30 to 40 volts and 5 to 10 amperes. A trace of alkali 
in the water causes formation of finer particles, presumably owing 
to the stabilising effect of the hydroxy! ion. The disintegration is 
chiefly at the cathode. 

The method is not satisfactory with organic liquids, because two 
much decomposition of the liquids takes place. Svedberg found 
empirically that this decomposition could be decreased very much 
if the current density were made as small as possible. ^^ He there- 
fore used an oscillatory discharge from an induction coil with a 
condenser in parallel or in series. The best results are obtained 
with large capacity, small self-induction, low resistance, and short 

5* Zeit. Kolloidchemie, 14, 65 C19U). 

5" Desch, The Chemutry and Testing of Cement, .58 (1911). 

" Bredig, Zeit. EleUroeheime, 4, ^U ("1898) ; Zeit. Phys. Chem. 31, 258 (1899). 

55 Svedberg, 424. 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 7 

arc. By this improved method Svedberg succeeded in preparing 
colloidal solutions of all the metals, including the alkali metals. 
Liquid methane, ether and isobutyl alcohol at low temperature were 
especially satisfactory with the metals of the alkalies and the alkaline 
earths. The order of disintegration of some of the metals under 
similar conditions was found to be Fe, Cu, Ag, Al, Ca, Pt, Au, Zn, 
Sn, Cd, Sb, Tl, Bi, Pb, the iron being the least rapidly disintegrated 
and the lead the most rapidly disintegrated. There is no apparent 
relation either with the order of the boiling-points or with the order 
of disintegration by cathode rays or canal rays. 

5. Electrochemical Disintegration. — With a lead cathode in caustic 
soda solution, the lead disintegrates when the current density exceeds 
a critical value, and the solution is coloured black like ink, with fine 
particles of metallic lead.^^ This is due to the temporary formation 
of a sodium-lead alloy, which then disintegrates in contact with 
water. Similar results can be obtained with cathodes of tin, bismuth, 
thallium, arsenic, antimony, and mercury. E. Muller^*^ obtained 
colloidal solutions of tellurium with a tellurium cathode. This 
seems to be due to the formation of polytellurides, which break 
down and set free tellurium. In the presence of oxygen there may 
also be an oxidation of a telluride. Fischer^^ has obtained metallic 
copper in the solution by using a high current density with a copper 
anode in sulphuric acid. Cuprous sulphate is formed, which breaks 
down to metallic copper and cupric sulphate. This experiment has 
not yet been made to give colloidal copper ; but this could probably 
be done if one were to add a suitable protecting colloid. The 
disintegration of all electrodes by an alternating current when the 
current density is high is undoubtedly due to the temporary formation 
and subsequent breaking down of a hydrogen or metallic alloy. 

Three classes of colloidal solutions have been distinguished, in 
which the stabilisation is due : to adsorbed liquid ; to adsorbed 
non-electrolyte, which may be in true solution or may be itself in 
colloidal solution ; and to an adsorbed ion. The last case is the 
easiest one to treat theoretically and is therefore taken up first. So 
long as the particles are all charged positively or all charged nega- 
tively, they will repel each other and will not coalesce. If the charge 
is neutralised or counter-balanced in any way, the particles will 
agglomerate'^ unless some other factor comes in. If a suspension is 
stabilised by the preferential adsorption of hydrogen ion from 
hydrochloric acid solution, the solution contains free hydrogen ions, 
free chlorine ions, and the adsorbed hydrogen ions which make the 
suspension behave like a cation though with a different migration 
velocity from that of hydrogen. If the suspension is made to adsorb 
an anion in an amount equivalent to the hydrogen ion adsorbed, the 

» Keed, Juur. Franklin Intt. 139, 283 (1895). 

Bredig and Haber, Ber. deuUche. Chem. Ges. 31, 2741 (1898). 
Haber and Sack, Zeit. Ulektrochemie 8, 245 (1902) ; Zed. Anorg. Chem. 34, 286 
(1903). 

«" Zeit. EleUrochemie H, 521, 701 (1905). 

Haber, Ibid. 11, 660, 827 (1905). 
6' Ibid. 9, 507 (1903). 

« Hardy, Zeit. Phys. Chem., 33, 385 (1900). Burton, Phil. Mag. (6), 12, 472 
(1906) ; 17, 683 (1909). 

20895 A 4 



8 



REPORTS OS THE STATE OF SCIENCE. 1918. 



suspended particles will be electrically neutral. This can be done 
by adding an electrolyte with a readily adsorbed anion. Since this 
is a matter of selective adsDrption, the concentration of the added 
anion necessary to cause an adsorption equivalent to the hydrogen 
adsorption will vary with each anion. To put the matter more 
generally, the amount of an electi'olyte necessary to precipitate a 
colloidal solution will vary with the nature of the cation, the anion, 
and the dispersed phase. While it is generally true that an ion of 
higher valance will be adsorbed more strongly than one of lower 
valence, this so-called law of Schulze*'^ is only a first approximation 
and should be considered only as a guide. 

That some univalent ions are absorbed more strongly by some 
substances than some bivalent or trivalent ions is shown clearly in 
data by Oden on colloidal sulphur^^, given in Table I. In the second 
column are the liminal concentrations necessary to coagulate 
the sulphur, given in gram atoms per litre of the cations ; in the 
third column are given the reciprocals of those values, the so-called 
atomic precipitating powers. 



Table I. 
Coagulation of Sulphur at 18°-20°. 



Salt. 


Liminal value gram-atoms 


Atomic precipitating power 




Cations per litre. 


of cation. 


HCl 


6 


0-16 


LiCl 


0-913 


11 


NH4CI 


0-435 


2-3 


(NH4)2S04 


0-600 


1-7 


NH4N01 


0-506 


2-0 


NaCl 


0-1.53 


6-1 


NaoSO^ 


0-176 


5-7 


NaNOs 


0-16.-5 


6-1 


KCl 


0-021 


47-5 


KoSOj 


0-025 


39-7 


KNO3 


022 


45-5 


RbCl 


0-016 


63 


CsCl 


0-009 


108 


MgSOj 


0-0093 


107-5 


Mg N03)s 


0-OOSO 


125 


CaCl2 


0-0041 


245 


Ca(NO,).. 


0-0040 


247 


Sr(N03)2 


0-0025 


385 


BaCl, 


0-0021 


475 


BaCNOs).. 


0-0022 


461 


ZnSOj 


0-0756 


13-2 


Cd(NO:0-. 


0-0493 


20-3 


AICI3 


0-0044 


227 


CUSO4 


0-0098 


102 


Mn(NO:0' 


0-0096 


105 


NiCNOs)- 


0-0446 


22-4 


UOaCNOOa 


0-0137 


73 



63 Jour. Prakt. Chem. (2), 25, 431 (1882) 
Chem.., 19, 364 (1915). 

«< Drr KiilloideScha-rM, 156 (1912). 



27, 320 (1 884). Bancroft, Jour. P/,ys. 



ON COLLOID CHEMISTKY AND ITS INDUSTRIAL APl'LICATIONS. 9 

Under the conditions of Oden's experiments, snlphur is a 
negative colloid, and the precipitation is therefore due to an 
adsorption of cations. The first thing to be noticed is that 
hydrogen ion is not adsorbed stronglj- by sulphur, the precipitat- 
ing power of hydrochloric acid being much less than that of 
lithium, ammonium, sodium, potassium, rubidium, or esesium 
chloride. Instead of these univalent cations precipitating at the 
same concentration, the required concentration of lithium 
chloride is, in round numbers, one hundred times that of csesium 
chloride. The liminal values for barium and strontium are 
nearly equal, but calcium chloride requires a distinctly higher 
concentration. If we take the different bivalent ions the values 
range from 0'0T56 for zinc to 0'0022 for barium, a ratio of over 
thirty to one. The univalent csesium.ion has a greater precipitat- 
ing power than the bivalent zinc, cadmium, nickel, and uranyl 
ions; and about the same precipitating power as the bivalent 
copper, manganese, and magnesium ions. The trivalent 
aluminum ion has about the same precipitating power as the 
bivalent calcium ion, and distinctly less precipitating power than 
bivalent strontium and barium ions. The specific nature of the 
adsorption conies out extraordinarily clearly with sulphur, about 
the only orthodox thing being that nitrate, chloride, and sulphate 
behave practically alike, though even here Oden considers that 
sulphate has a slight protecting action. This specific nature 
appears more clearly, perhaps, if we arrange the cations in order, 
the one with the greatest precipitating power coming first: Ba, 
Sr > Ca, Al > Mg, Cs, Mn, Cu > UO2 > Rb > K > Ni, Cd, Zn > 
Na > NH4 > Li > H. 

Sulphur is admittedly an extreme case, but Freundlich^^ 
gives data for colloidal platinum from which I deduce the order : 
Al, Pb > Ba, UO2 > Ag > K, Na. Bivalent lead has practically 
the same precipitating power as trivalent aluminum. Univalent 
silver is nearer to bivalent uranyl and barium than to univalent 
potassium and sodium. If more cations had been studied we 
should very likely have got more distinct evidence of specific 
action. As it is, it takes 130 millimoils NaOH per litre to 
coagulate the platinum, and only 2b millimols NaCl. The change 
from chloride to hydroxide has a more marked effect than the 
change from sodium to barium. It seems very probable that 
barium hydroxide would have no greater precipitating power 
than sodium chloride. From Pappada's experiments with col- 
loidal silver'^'^ I deduce the following order of adsorption : Al 
> Ba, Sr, Ca > H > Cs > Rb > K > Na > Li. From these data 
Pappada concludes that the migration velocity is the determining 
factor with the univalent cations; but this cannot be true. The 
difference between aluminum and hydrogen is not very great, 
one drop of M/10 HCl producing a coagulation and one drop 
M/20 AlCl,. In tenth-normal solutions potassium iodide, 
nitrate, and sulphate produce no coagulation. The reason given 
by the author is that these anions react with the colloidal silver, 

« KapiUarchemie, 353 (1909). 



10 



REPORTS ON THE STATE OF SCIENCE. 1918. 



In normal solutions the iodides, nitrates and sulphates are said 
to precipit-ate at the same concentrations as the corresponding 
chlorides and bromides. The effect of concentration is a little 
obscure in other respects since 5 or 6 drops of normal KCl precipi- 
tate 2 cc. 0'06 per cent. Ag, whereas it takes only 30 drops N/10 
KCl to produce precipitation. The essential thing, from my 
point of view, is that the different univalent cations have different 
liminal values ; the difference between hydrogen and lithium is 
greater than that between hydrogen and aluminum. 

From experiments on mastic®'' we get the data given in 
Table II. 



Table II. 

Coagulation of Mastic. 



Salt, 


Liminal value, gram 


Atomic precipitating 


atoms. 


power of cation. 


NaCl 


10 


1 


A?NO-, 





125 


8 


HgNOa 





00125 


800 


HCl 





010 


100 


CaCla 





025 


40 


BaCl.> 





025 


40 


ZnSO, 





050 


20 


AUCSOs). 





0004 


2,.500 


AlKNOs)^ 





0004 


2.500 


FeCls 


0-0003 


3,300 



If we consider the mercury in mercurous nitrate as a univalent 
ion, it is very much out of place, precipitating at much lower 
concentrations than the barium, calcium, and zinc salts. Of 
course, the fof-mula should be written Hg2(N0,)2 with Hg, as a 
bivalent ion.** In this case the precipitating power becomes 
1,600 instead of 800, which puts it up much nearer the trivalent 
cations than the bivalent ones. The order of cations is : Fe, 
Al > Hg2 > H > Ba, Ca > Zn > Ag Na. Only three anions are 
given in the table, so it is impossible to tell what effect the anions 
have. A good many experiments have been made on mastic with 
different acids, but the degree of electrolytic dissociation varies 
so as to make these results inconclusive. With Prussian blue 
Pappada^^ found the order of the cations to be : Fe, Al, Cr > Ba, 
Cd > Sr, Ca > H > Cs >Rb >K >Na >Li. Sulphates, nitrates, 
chlorides, bromides, and iodides all behaved alike. Practically 
the same order of the cations was obtained for copper ferro- 
cyanide.'^" In the cases studied by Pappada the specific adsorp- 
tion appears to play a very small part. The data for arsenic 

«s Pappada. Gazz. chim. ital. 42, I, 263 (1912). 
6^ Freundlich, Kapillarchemie, 367 (1909). 
«8 Ogg, Zeit. vhys. Chem. 27, 285 (1898). 
69 Zeit. XolJoidchemie, Q, 83 (1911). 
7" Pappada, Znt. Kolloidchemie, 9, 136 (1911) 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 11 

sulphide/* however, give variety enough. The order of cations 
is Ce, In, benzidine, Al > new fuchsine, crystal violet > quinine > 
morphine, UO2 Sr. Ca > Be, Zn, Ba > Ng > p-chloraniline. 
toluidine > aniline > strychnine > guanidine > H > K> Na >Li. 
The organic cations come in where they please and play havoc 
with any rule as to valency. The chlorides and nitrates give 
practically the same values, and the sulphates are not far out of 
line, though it seems probable that the restraining power of 
sulphate is rather greater thau that of chloride or nitrate. The 
liminal values in gram atoms of the cation per litre are 0"0056, 
0-0066, 0-0086, 0-110, and > 0-250 for potassium nitrate, sulphate, 
formate, acetate, and citrate, from which one can deduce that the 
order of adsorption of anion is: citrate > acetate > formate > sul- 
phate > nitrate, chloride. It is a great pity that Freundlich did 
not try other combinations, such as barium acetate, for instance. 

From the experiments on hydrous ferric oxide, ^- the order of 
adsorption of the precipitating anions appears to be Cr^O^ > SO4 
> OH > salicylate benzoate >l:ormate >C1 > NO3 >Br >I, while 
the order for the cations is : H > Ba > Mg > Tl, Na, K. The 
univalent ions do not all behave alike, and neither do the bivalent 
ones ; but the upholders of Schulze's law can comfort themselves 
with the fact that the two sets do not overlap except in the case 
of hydrogen. There is no such comfort in the case of albumin. 
I have shown" that the probable order of adsorption of anions, 
so far as known, is : sulphocyanate, iodide > chlorate > nitrate > 
chloride > acetate > phosphate > sulphate > tartrate, the sulpho- 
cyanate ion being adsorbed the most and the tartrate ion the 
least. Here there is nothing even to suggest Schultze's law, 
and the firm belief which most people have in Schultz-e's law is 
probably one reason for the marked failure to account satis- 
factorily for the phenomena with albumin. With the cations 
albumin appears to be fairly orthodox, for the order of adsorption 
appears to be Th, UO2 > Cu, Zn > Ca > Mg > Li > K, Na > NH 
though even here the lithium stands higher m the series than it 
has been found with other substances. 

While there is unquestionably a tendency for ions of a higher 
valence to be adsorbed more strongly than ions of a lower valence, 
the experiments which have been cited show that there are many 
exceptions, and that the fundamental rule is that the axlsorption 
is specific both as regards the adsorbing substance and the ion 

adsorbed. . . ,• j 

Albumin is a specially interesting ca.se because it is peptised 
readilv by cations or anions. When it is negatively charged, as 
in a slightly alkaline solution, a strongly adsorbed anion will 
make it more negative and more stable Consequently, Precipita- 
tion by a sodium salt will be more eftective the less readily the 
anion is adsorbed. On the other hand, m acid solutions the 
n Freundlich, Kapillarchemie, 351 (1909). Freundlich and Scliucht, Zeit. phy.. 

'':"F?e^uViuci'S«a.r;,.«.>, 352, .58, (1909> Zsigmondy, K„Uoi,lcke„ne, 18i 
(1912). Pappada, Znt. Knlloidchemie, 9. 2.« (UU). 
"Bancroft, Jour. Pjujx. Chvm. 19, H-''-^ (I'-'l^)- 



12 REPORTS ON THE STATE OF SCIENCE. — 1918. 

sodium salt witli the luost strougly adsorbed auion will be the 
most effective in causing- precipitetion. Neg'atively charged 
albumin is precipitated readily by sodium chloride, and not at 
all by sodium iodide, while positively charged albumin is precipi- 
tated by sodium iodide much more readily than by sodium 
chloride. 

If one over-runs the point of electrical neutrality, the suspen- 
sion may become stable again because it is stabilised by preferen- 
tial adsorption of an ion having the opposite sign. If one adds 
a little less than the equivalent amount of a dilute potassium 
bromide solution to a dilute silver nitrate solution, one gets a 
positively-charged colloidal solution of silver bromide because 
the silver bromide is stabilised by adsorbed silver ions. If one 
adds slightly more than the equivalent amount of the potassium 
bromide soliition, there is obtained a negatively-charged colloidal 
solution of silver bromide, stabilised by adsorbed bromine ions. 
If more bromide solution is added, the silver bromide will coagu- 
late because there will come a point at which the slight adsorp- 
tion of the potassium ion counterbalances the adsorption of the 
bromine ion. In other words, silver bromide precipitates, when 
there is a distinct excess of silver nitrate, stays in suspension as a 
positively charged colloid when there is only a slight excess of 
silver nitrate, precipitates, when the suspension becomes electri- 
cally neutral, stays in suspension as a negatively charged colloid 
when there is a slight excess of potassium bromide, and precipi- 
tates when there is a distinct excess of potassium bromide. At 
the two ends of this series there is also the possibility of true 
solution of silver bromide in silver nitrate or potassium bromide. 

An interesting case of the precipitation of a colloid by an 
electrolyte is to be found in the action of sea-water on muddy 
river water. Skey'^* pointed out that suspended mud is precipi- 
tated by electrolytes, and Waldie^^ has discussed the clearing of 
the water of the Hooghly. When a river flows into the ocean, the 
current becomes less, and some of the suspended mud is dropped 
on this account; but that is relatively unimportant in many cases. 
Schloesing'*^ called attention to the fact that the formation of 
deltas is due primarily to the coagulation of the suspension by 
the electrolytes in the salt water. Another interesting case of 
the neutralisation of an electrical charge is the precipitation of 
positively charged colloids by ^rays."^ 

Since the important thing in the neutralisation of an adsorbed 
ion is the adsorption of an ion of the opposite charge, we may 
get neutralisation when we have a colloid with the opposite 
charge. In other words, we may neutralise an adsorbed ion 
with another adsorbed ion instead of by a free ion. The usual 
statement is that sols having the same charge do not affect each 
other perceptibly, while sols having opposite charges precipitate 

"* Chem. News, 17, 160 (18681. 

" Chem. News, 30, 37 (1874). 

~^Joi<r. Chpw. 6'(.c., 24, 750 n871). 

" Hardy, Jour. Phi/siolor/t/, 29, 29 (1903). Hober, PhysiUaU.iche Chemie der 
ZeUe iind Zpwehc, .S32' (1911') ; Burton. T/ir Physical Properfie.^ uf Colloidal 
Solutions. 172 (1916). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 13 

e^fh other.'"* Neitlier oi' tliese stjitement.s is as accurate as it 
should be. I shall take up first the case of sols having oppasite 
charges. Positive and negative colloids will precipitate each 
other when in proper proportions and provided adsorption takes 
place. ^'•' I see no theoretical reason why we should not have a 
positively charged and a negatively charged sol, neither of which 
adsorbed the other to any appreciable extent. In that case these 
two sols would not precipitate each other. Since complete 
neutralisation takes place only when one sol has adsorbed the 
amount of the sol carrying an equivalent amount of the ion 
having the opposite charge, it follows that the amount of one sol 
necessary to precipitate a given amount of another sol will vary 
with the degree of adsorption; it will therefore be a specific 
property and not an additive one. This can be tested experi- 
ment-ally on data by Biltz given in Table III.'*" 

Table III. 

1 ■ -t ing. crold completely precipitated by 

CeO, FejOj ThO; ZrO; CrgOa AUOa 

4 3 2-5 1-6 0-3 0-1 -02 mg. 

28 mg. Sb->03 completely precipitated by 
FeA ThOa CeOj ZrOj CrOj AI2O3 



32 20 11 6-5 3-0 2-0 mg. 

24 mg. AgoS.") completely precipitated by 

FeaOs ThO. CeO. ZrOz AL.O3 CrjOa 

13 6 4 2 2 0-5 m?. 

Alumina is more effective than chromic oxide in precipitating 
antimony sulphide, and much less effective in precipitating 
arsenic sulphide. The alumina must therefore be adsorbed more 
by antimony sulphide than chromic oxide, while the reverse must 
be true for arsenic sulphide. Cerium oxide is less effective than 
ferric oxide and thorium oxide in precipitiating gold, but is more 
effective than either of these in precipitating the sulphides of 
antimony and arsenic. The phenomenon is thus specific, vaiying 
with the nature of the two colloids. This seems not to have been 
realised before. In fact, Freundlich says definitely*' that 'one 
seems to find approximately the same order regardless of what sol 
is to be precipitated.' This st-atement is true, but it missed the 
important thing in the experiments, which was that the order 
was not always the same. 

We can now take up the case of sols having the same charge. 
The statement that neither has any perceptible effect on the other 
is based solely on the fact that no precipitation occurs. We 
know, however, that cases of adsorption are not limited to colloids 
or electrolytes having opposite signs. Charcoal adsorbs both 
bases and acids. Silver bromide ad,sorbs silver ions or bromine 

"Freundlich, Kapillarchemie, 444 (1909). Z^igmondy, KoUaidchemie, 56 
(1912). Hober, PhysihalUche Chemie der Zelle uml Zewehe, 294 (1914). 
'» Bancroft, Jour. Phys. Chem., 18, 5.5.5 (1914). 
«" Freundlich, Kapillarchemie, 44.5 (1909). 
»' Freundlich, Kapillarchemie, 44.5 (1909). 



14 REPORTS ON THE STATE OF SCIENCE. 1918. 

ions, as the case may be. There is, therefore, no theoretical 
reason why precipitated hydrous ferric oxide might not adsorb 
chromic oxide, and vice versa. If the precipitated substance will 
do this, there is no reason why the peptised substance should not. 
NageP^ has shown recently that this does occur, and that it 
accounts for the behaviour of mixtures of chromic and ferric 
salts with excess of alkali. Hydrous chromic oxide is peptised by 
caustic potash, while hydrous ferric oxide is not. If the 
chromium salt is present in large amount relatively to the iron 
salt, the ferric oxide will adsorb the peptised chromic oxide 
and be peptised by it, going apparently into solution. If the 
ferric salt is present in excess, it will adsorb the peptised chromic 
oxide, carrying it out of the liquid phase. It is to be noticed 
that the chromic oxide, when in excess, acts as a so-called protect- 
ing colloid to the iron oxide. Everybody is familiar with the 
fact that gelatine is adsorbed by colloidal gold, for instance ; 
but that is usually treated under the heading of protective colloids 
rather than under the heading of mutual action of two colloids. 
The case of chromic and ferric oxides is merely another illustra- 
tion of the fact that the distinction between a suspension colloid 
and an emulsion colloid is now arbitrary and unisatisfactory.*^ 

Coming back for a moment to the behaviour of two oppositely 
charged colloids, there is a special hypothetical case which is 
perhaps worth mentioning. Suppose we have two sets of finely 
divided particles, neither of which adsorbs the other appreciably, 
and let us also suppose that one set of particles adsorbs a given 
cation very strongly, while the other set of particles adsorbs a 
given anion very strongly. If we take a mixture of these two sets 
of particles and add a small amount of the salt of the given base 
and the given anion, we shall have a colloidal solution which will 
conduct electricity very well, but which will contain no free ionsto 
speak of because, by definition, the cations have been practically 
completely adsorbed by one set of particles and the anions by the 
other set of particles. This particular case has not been realised, 
but an intermediate one seems to have been found by McBain and 
Martin** in sodium palmitate solutions. 

' Most authors since Eahlenberg and Schreiner*^ have, as a 
matter of course, ascribed the conductivity exhibited by soap 
solutions largely to free alkali hydroxide. In previous papers 
from this laboratory the same tentative suggestion was made, but 
it was each time clearly stated that it was only a working 
hypothesis until these experimental data should be ascertained. 
Now it is certain that the conductivity of soap solutions is, only 
to a very minor extent, due to hydroxyl ions. Further, on 
account of the fact that the rise of boiling point in certain soap 
solutions is practically all required to account for the sodium ions 
alone, *^ the conductivity cannot be wholly ascribed to simple 

8» Jour. Phys. Chem. 19, 331 (1915). 

S3 Bancroft, Jour. Phy.<!. Chem. 18, 556 (1914). 

8* Jour. Chem. Soc. 105, 965 (1914). 

85 Zeit. Phys. Chem. 27, 552 (1898). 

SG McBain, Trans. Faraday Soc. 9, 99 ; Xeit. Kolloidchemle, 12, 266 (1913) 



O.V COI-LOID CMIEMISXRY AND ITS INDUSTRIAL APPLICATIONS. 15 

palmitate ious. The suggestion we made is that we have here 
a new type of aggregate or micelle, the mobility of whicli, owing 
to the reasons given in the i)aper cited, is conijjarable with that 
of a tnie anion. Of course, further investigations are i)roceeding 
in this laboratory in order to bring this to the test of direct 
experiment. Incidentally, the above shows, further, that undis- 
sociated soap is present chiefly or entirely in colloidal form.' 

As I see the matter, the sodium palmitate is hydrolysed and 
the hydroxyl ions are adsorbed to a great extent by the undis- 
sociated palmitate, and possibly by the insoluble palmitate acid 
also, though this seems less probable. Tlie adsorbing substance 
thus becomes the anion, owing to the adsorbed hjdroxyl. Because 
of electrometric measurements, McBain*' considers that there is 
practically no hydrolysis. Electrometric measurements only 
show the concentmtion of hydroxyl ions in solution. I do not 
believe for a moment that an adsorbed hydrogen ion or hydroxyl 
ion behaves electrometrically like a free hydrogen or hydroxyl 
ion. An adsorbed chlorine ion, for instance, would not give a test 
with silver nitrate. Under these circumstances the electrometric 
measurements are satisfactory for showing the concentration of 
hydroxyl ions in the solution, but they are utterly worthless for 
showing the degree of hydrolysis of sodium palmitate. For the 
same reason I am very sceptical as to any conclusion in regard to 
albumin solutions which is based on electrometric measure- 
ments.^^ 

So-called irregular series *® have been observed when a suspen- 
sion of a positively-charged colloid is added to a suspension of a 
negatively-charged colloid. When increasing concentrations of 
aluminium sulphate were added to a negatively-charged solution 
of mastic there was at first no precipitation, and the suspension 
was charged positively because the mastic was present in excess. 
At higher concentrations of aluminum sulphate, the suspension 
became electrically neutral, and complete precipitation took 
place. At still higher concentrations the mastic was held in 
suspension by the hydrolysed alumina, and the suspension was 
charged positively. At still higher concentrations of aluminum 
sulphate complete precipitation occurred. This apparently 
abnormal result is due to the fact that the experiment is not 
exactly what it purports to be — the addition of one colloidal solu- 
tion to another. Instead of adding a colloidal solution of 
alumina, there was added a so-called solution of aluminum 
sulphate, which hydrolysed to colloidal alumina and sulphuric 
acid, with possibly some aluminum sulphate left unchanged 
especially in the higher concentrations. The amount of free 
sulphuric acid is always equivalent to the amount of alumina, 
and the two concentrations increase proportionally. The so- 
called abnormal precipitation at the higher concentrations is 
merely a precipitation by sulphate ions, and is absolutely normal. 

«' McBain and Martin, Jour. diem. Sor. 105, 9'i7 (101 1). 

8« Bancroft, Jour. Phi/.t. Chem. 19, 349 (191.5). '. . 

89 Neisser and Friedmann, Zeit. aiiflcw. Cliem. IQO^i J9i>3 ; ^echhold. /^eit. 
Phys. Chem. 48, 285 (1904) ; Buxton and Teague, Ze\t Phyx. Chem 57, 47, 64 
(1907) ; Freundlich, A77;«7ZarcAe7re!V, 402 (1909). 



16 REPORTS ON THE STATE OF SCIENCE. 1918. 

Since the precipitation oif one colloid by another may take place 
within a relatively narrow range of concentrations, it is not 
surprising that people have postulated the existence of definite 
chemical compounds in order to account for the precipitates. 
The literature on the subject is in a worse state even than that on 
the so-called basic salts. For instance, ferric arsenate, aluminum 
silicate, stannic phosphate, and cupric eosinate are not formed 
under ordinary conditions by precipitation from solutions. The 
precipitation is due to the mutual coagulation of two colloids, 
though the resulting precipitate may simulate a compound to the 
extent that it may be peptised without change under certain 
conditions. 

While the theory of peptisation and precipitation, as outlined, 
accounts satisfactorily for most of the facts, there are certain 
points which are not covered by it at present. A mixture of the 
two water-peptisable colloids, gelatine and gum arable, is said to 
behave exactly like casein.'" Under certain conditions gelatine 
and tannin form an insoluble or non-peptisable mixture;®^ but 
we do not know why. The case of chrome tanning is not difficult 
because the chromic oxide would not normally be peptised under 
the conditions of the experiment, and it has been shown that 
there is no necessary change in the gelatine.'^ We also cannot 
account at present for the stability or instability of metal sols in 
different organic liquids ; in this case as well as in the other 
two, the trouble is in our ignorance of the facts and not in any 
shortcomings of the theory. 

EMULSIONS. 
By E. Hatschbk, Sir John Cass Technical Institute, London. 

The term Emulsion is used in the following to denote a disperse 
system both phases of which, considered in bulk and at ordinary 
temperatiire, ure liquid. The qualifying clause, although not 
generally stated in such explicit tern.s, seems desirable as, on one 
hand, the distinction between liquid and solid becomes somewhat 
vague with particles approaching ultra-microscopic dimensions, 
while, on the other, the same system, e.g. rosin in water, may be a 
suspension at lower and an emulsion at higher temperature. 

One characteristic of emulsions, which distinguishes them sharply 
from systems with solid disperse phase, follows immediately from the 
definition : there is no upper limit to the ratio : Volume of disperse 
phase/Volume of continuous phase. With solid or, better, undeform- 
able particles of disperse phase there is such a limit (apart from the 
ideal case of space-filling polyhedra of equal size) which, for 
spherical particles of uniform radius, is approximately 74/26. 

It is obvious that, with a liquid or deformable disperse phase, 
spherical particles in closest contact do not constitute a limiting case, 

90 Tiebackx, Zeit. Kolloidchemie, 8, 198, 238 (1911). 

91 Wood, Jour. Sec. Chem. Ind., 27, 384 (1908). 
Von Schroeder, Zrir Kenntnisx des Gerbeprozesses. 
Levites. Zeit. Kolloidehemie, 8, 4 (1911). 

?2 Lumiere and Seyewetz, B^M. Soc. Chim., Paris (3) 89, 1077 (1903). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 17 

as — at least theoretically — a further increase in the relative volume 
of disperse phase can lead to flattening at the points of contact of 
contiguous spheres and eventually to a polyhedral structure of the 
system. A limit is only reached when the thin films of continuous 
phase which separate the polyhedra of disperse phase are no longer 
capable of cohering. The practical possibility of such systems is 
demonstrated by some of S. U. Pickering's emulsions with up to 
99 per cent, of disperse phase. The complete conditions for the 
stability of such films will be discussed further on. but it can be 
said at once that a low inter-facial tension is, if possibly not sufficient, 
certainly necessary. 

Conversely, emulsions with a very low content of disperse phase, 
in which the particles are small and separated by layers of continuous 
phase of some thickness compared with the extent of interface, are 
possible and moderately stable even when the interfacial tension is 
high, viz. of the order of 30 to 40 dyne/cm. Such emulsions may be 
produced by agitation, by distilling the two phases together, or by 
'precipitating 'an alcohol or acetone solution of the disperse phase with 
a large excess of water. The properties of such emulsions with a 
disperse phase consisting of mineral oils, aniline, nitrobenzene, oleic 
acid or castor oil, amounting to one part in a thousand, or less, of the 
total volume, are throughout those of fine suspensions or of suspen- 
soids. The (negative) electric charge is of the same order as on 
suspensoid particles (Lewis) ; is similarly afltected by hydrogen and 
hydroxyl ions (Ellin) ; the maximum concentrations at which the 
emulsions are stable are of the same order as for suspensoid sols 
(Lewis), and the phases may be separated by filtration through 
suitable septa under considerable pressure (Hatschek). The effect 
of interfacial tension is altogether subordinate to that of the electric 
factors. 

Emulsions containing larger percentages of disperse phase than 
those meationed, in particles of microscopic or approaching micro- 
scopic size, are stable, or in fact anything more than transient, only 
when the interfacial tension between the phases is low, as has already 
been mentioned. In the emulsions occurring in nature, such as 
milk or latex, this is generally brought about by the protein content 
of the continuous phase, while in the emulsions prepared artificially 
the agent which lowers the interfacial tension is very generally a 
soap. The stability of such emulsions is, however, again dependent 
on the phase ratio and is generally not complete unless this approaches 
the figure corresponding to closest packing. Thus, if oil and a dilute 
soap solution are shaken until the whole of the oil is dispersed, the 
resulting emulsion separates into a layer of soap solution containing 
only a very small fraction of oil and a ' cream ' containing 75 per 
cent., or more, of oil ; the latter is stable, provided the walls of the 
containing vessel are wetted only by the continuous phase and no 
oil in bulk is in contact with the cream. The rate of separation 
depends naturally on the difference in density of the phases, the 
viscosity of the continuous phase and the degree of dispersion : it is 
obvious, although the case has chiefly a theoretical interest, that a 
system stable in all ratios is conceivable if both phases have the 
same density, e.g. castor oil in water with a little alcohol. 



18 REPORTS ON THE STATE OF SCIENCE. 1918. 

The connection between low interfacial tension and emulsification 
was first insisted on by Quincke, but the principal quantitative 
investigations are due to Donnan. They comprise experiments 
carried oi^t with the drop pipette on the emulsification of glycerides 
in alkali solution, which show, in agreement with Quincke, that free 
fatty acid, i.e. the possibility of soap formation at the interface, is a 
necessary condition if emulsification is to take place; determinations 
of the drop numbers for hydrocarbon oils discharged into solutions 
of salt of the fatty acids, and experiments in which the hydrocarbon 
oil was dispersed in these solutions by shaking under strictly defined 
conditions. The two last series give concordant results and show 
that the first salt of the fatty acid series to exert an appreciable 
emulsifying action is the one which shows the first marked reduction 
of surface tension, viz. that of lauric acid. Donnan also finds that 
there is an optimum concentration of soap, and explains it as due to 
the balance between the reduction of interfacial tension, which 
promotes, and the electrolyte effect, which counteracts, dispersion. 

A similar result, viz. that increase of soap concentration beyond 
a certain limit was detrimental to emiilsification, had been obtained 
by S. U. Pickering. According to him the optimum concentration 
depends both on the phase ratio and on the sitosolute volumes of the 
phases, so that no simple explanation appears to oft'er itself. The 
same author also gives a number of experiments in which the emul- 
sifying agent is not in solution — either true or colloidal — but a 
precipitate such as ' basic iron, copper or nickel sulphate,' i.e. the 
precipitates formed by adding lime water to the respective sulphates. 
If water containing one of these substances is agitated with oil — 
more particularly mineral hydrocarbons of 250° to 359° boiling-point 
and about 0*85 sp. gr. — the oil is completely emulsified. After an 
examination of various finely divided solids which show only a 
transient effect or none at all, Pickering comes to the conclusion that 
the chief factor in the formation of stable emulsions of oil as disperse 
phase in water is the existence of a layer of small solid, non- 
crystalline particles which are more easily wetted by water than by 
oil (the italics are mine, E. H.) at the interface. 

While Pickering thus concludes that a low interfacial tension is 
not the principal, or in fact a necessary, condition of emulsification, 
the discrepancy between the two views is probably only apparent, at 
any rate if the ' solid ' state of the particles in the interfacial layer is 
not insisted upon. If low tension is not the direct agent it is never- 
theless active indirectly in bringing about — in such solutions as alone 
come into question — the formation of absorption films having some 
of the properties postulated. On the other hand, the substances used 
by Pickering would obviously not accumulate at the interface (more 
strictly on the water side of it) unless this arrangement led to a 
lowering of the interfacial tension. 

That a film or membrane covering the whole of the interface is 
a necessary condition of stability in emulsions is the conclusion 
pronounced by W. D. Bancroft after a most exhaustive review of the 
available material. The relative solubility of this film in the two 
phases, or the difference in interfacial tensions between them and 
the film, determines the nature of the emulsion, i.e. which of the 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 19 

two phases, in given conditions, will be the disperse and which the 
continnous phase. 

These views derive strong confirmation from a series of experi- 
ments by G. H. A. Clowes. He prepares an emulsion with oil as 
disperse phase by shaking olive oil with a dilute solution of NaOH 
in water. If a quantity of CaCh. slightly in excess of the equivalent 
of the NaOH is added to this emulsion, it transforms itself sponta- 
neously into one having water as disperse and oil as continuous 
phase. This can be re-converted into the original emulsion by 
adding NaOH until the original OH' concentration is restored. 
Magnesium, iron, and aluminium have an effect similar to that of 
calcium. Since the oleates of these metals are much more soluble in 
oil than in water, their formation would cause a considerable reduc- 
tion in the interfacial tension between the film and the oil phase, so 
that the film would tend to become convex towards the oil and 
concave towards the aqueous phase, i.e. oil would become the con- 
tinuous phase and water the disperse. The whole process is an 
actual reversal and is therefore sharply distinguished from such 
phenomena as the separation of emulsions into two (no longer 
disperse) phase by the addition of electrolytes or of substances which 
decompose the material of the interfacial film. 

Evidence similar, and complementary, to that afforded by Clowes's 
experiments is provided by an investigation by A. U. M. Schlaepfer, 
the object of which was to produce emulsions of water dispersed in 
oil by using a finely divided substance more completely wetted by 
oil than by water : soot accomplished the desired result. 

Earlier experiments by Walter Ostwald, made with the intention 
of determining the type of emulsion which would result from the 
agitation of oil with water only, showed that either type was possible 
and that the result depended largely upon secondary factors, such as 
the state of the containing vessel and its previous wetting by one or 
the other phase. Conclusions drawn by this author regarding the 
limiting phase ratio have been proved incorrect both theoretically and 
experimentally. Donnan also found that the state of the vessel intro- 
duced considerable experimental complications. Although the method 
used by these and other authors — viz. agitation of the total volumes of 
both phases— is perhaps as good as any other arbitrary method, it 
neither corresponds to the probable process of formation of natural 
emulsions nor to the technical methods adopted for the production of 
stable emulsions, in which the gradual addition of the disperse phase 
during, and 2^ciri passu with, the process of dispersion is generally 
considered an essential condition of success. 

The theoretical interest of emulsions is considerable and is likely 
to become even greater. Viewed as disperse systems of two liquid 
phases they are the only ones in which the phase ratio is accurately 
known and therefore specially adapted for studying the physical 
properties, e.g. the viscosity of such systems. They have also 
acquired very great importance in biology in view of some modern 
hypotheses on the constitution of protoplasm, the possible existence 
of lipoid films and cognate phenomena, such as the action of 
' antagonistic ' ions and of anaesthetics. While at present the con- 
clusions respecting such complicated problems drawn from the study 



20 REPORTS ON THE STATE OF SCIENCE. .1918. 

of comparatively simple and coarse systems may perhaps constitute 
a theoretical edifice somewhat disproportionately large for its slight 
experimental foundation, there can be no doubt that the trend of 
research is in the right direction. 

Technically also emulsions are of considerable importance. They 
are employed — speaking, of course, very generally — where it is 
necessary to administer or exhibit a liquid in a varying degree of 
dilution, while the ordinary solvents for it are inadmissible on 
economical, technical, or physiological grounds. In such cases, or in 
a great number of them, the active liquid may be used as disperse 
phase of an emulsion, the continuous phase of which is so selected as 
to be indifferent ; in addition it must wet, or be absorbed by, 
the surfaces to which the emulsion is eventually applied. Examples 
are : the medicinal emulsions of such liquids as cod-liver oil or 
petroleum (in which further desirable ingredients like malt extract, 
hypophosphites, &c., may be in solution in the aqueous phase) ; 
emulsions of cresols and other substances for use as antiseptic and 
anti-parasitic preparations ; fat solvents such as carbon tetrachloride 
emulsified with ' monopol ' soap (obtained by saponifying sul- 
phonated castor oil) ; emulsions of fats in a great variety of menstrua 
and used as leather 'foods' and dressings, &c. The preparation of 
such emulsions is of course generally a trade secret ; as regards the 
emulsifying agent, this is, however, very generally a soap in all 
technically used emulsions. 

Emulsions occur in industrial processes as undesirable by-products, 
such as very persistent emulsions of mineral oils or of wool-fat in 
the course of refining ; the condense v^ater from reciprocating 
engines, which contains the oil used in the lubrication of slide valves 
and cylinders and is a very perfect type of the stable oil-water 
emulsion, &c. In all these cases the means of preventing the forma- 
tion of an emulsion, or of separating it when formed, can be deduced 
from the theoretical considerations set forth above, although unfortu- 
nately their practical application is in many cases somewhat difficult. 

BiBJ.IOGEAPHY. 

Wm. C. McC. Lewis, The size and electric charge of oil particles in oil-water 
emulsions, ' Koll.-Zeitschr.', 4, 211, 1909. 

Size and charge in highly disperse and dilute oil-water emulsions are of the 
same order as in suspensoid sols. 

Wm. C. McC. Lewis, The surface tension of colloid and emulsoid particles and 
its dependence on the limit size of the latter, ' Koll.-Zeitschr.', 5, 91, (1909). 

T. Beailsfoed Robertson, Notes on some factors which determine the 
constitution of oil-water emulsions, ' Koll.-Zeitschr.', 7, 7, 1910. 

Walter Ostwald, Contributions to the knowledge of emulsions, ' Koll.- 
Zeitschr.', 6, 103, 1910. 

Experiments to determine which of two constituents will form the disperse 
phase under definite conditions of agitation, etc. The conclusion that closest 
packing of spheres constitutes a limiting phase ratio, pronounced by the author, is 
untenable. 

S. U. PiOKEEiNG, On emulsions, 'Koll.-Zeitschr.', 7, 11, 1910. 

Highly concentrated emulsions of mineral oil in soap solution (up to 99 per cent, 
disperse phase) ; emulsification by solid particles. 

E. Hatschek, The direct separation of emulsions by filtration and ultra- 
filtration, 'J. Soc. Chem. Ind.', 29, 3, 1910. 

E. Hatschek, The filtration of emulsions and the deformation of emulsified 
particles under pressure, ' Koll.-Zeitschr.', 7, 81, 1910. 



ON rOl.r.OlD OHKMISTRY AN]) ITS INDCSTRIAI, AIMTJCATIONS. 21 

Mathematical and experimental demonstration of the high rigidity of small 
liquid particles. 

F. G. DoNNAN and H. E. Potts, On the emuhification of hydrocarbon oils by 
aqueous solutions of fatty acid salts, ' Koll.-Zeitschr.', 9, 208, 1911. 

Experiments showing parallelism between the emulsifying effect of fatty acid 
salts and decrease in surface tension of their solutions. 

E. Hatschek, The stability of oil- water emulsions, ' Koll.-Zeitschr.', 9, 159, 1911. 

E. Groschdff, The stability of emulsions of water in hydrocarbon oils, ' Koll.- 
Zeitschr.', 9, 257, 1911. 

RiDSDALE Ellis, The properties of oil- water emulsions, ' Zeitschr. phyg. 
Chem.' : I. The electric charge, 78. 321, 1912; II. The stability and size of the 
particles, 80. 597, 1S112. 

A very complete experimental investigation showing similarity becwten oil- 
water emulsions and suspensoid sols. 

Wilder D. Bancroft, The theory of emulsification, ' J. phys. chem.'; I. 16, 
177 ; II. 16, 345 ; III. 16, 475 ; IV. 16, 739, 1912 ; V. 17, 501, 1913. 

A very complete critical review of the whole literature, summarised in the 
conclusion quoted above. 

G. A. H. Clowes, On reversible emulsions and the role played by electrolytes in 
determining the equilibrium of aqueous oil systems, ' Proc. Soc. for Exp. Biol, and 
Med.' ; 11, 1, 1913. 

G. A. H. Clowes, The action of electrolytes in the formation and inversion of 
oil-water systems, with some biological applications. 

This paper, like the preceding one, describes experiments with emulsions 
obtained by dispersing olive oil in dilute NaOH solution. By adding CaCl., in 
excess of the alkali they are spontaneously transformed into emulsions having 
water as disperse phase, which can be re-transformed into the first type by adding 
NaOH in excess. 

M. H. Fischer and M. 0. Hooker. On the formation and decay of emulsions, 
'Koll.-Zeitschr.' ; 18. 129, 1916. 

A. XJ. M. Schlaepfer, Water-in-oil emulsions, -J. Chem. Soc.', 113, 522, 1918. 

The author, following Pickering, concludes that a finely divided solid more 
easily wetted by oil than by water should be capable of producing emulsions with 
water as disperse phase and proves his conclusion experimentally by using soot as 
emulsifying agent. 

THE LIESEGANG PHENOMENON. 
By E. Hatschkk, Sir John Cass Technical Institute, London. 

This pbenomenon was observed by its discoverer, after whom it 
is called, when carrying out the following experiment in the course 
of some researches on Golgi's method of staining animal tissues with 
silver chromate : 

A glass plate is coated with 5 per cent, gelatin gel containing a 
small amount of potassium bichromate. A drop of strong silver 
nitrate solution is then placed on the gel and immediately begins to 
diffuse into the latter. The silver nitrate of course reacts with 
the bichromate in the gel, the products of reaction being silver 
bichromate and potassium nitrate. Although there is thus a con- 
tinous supply of both components, the insoluble silver salt is, 
however, not deposited in a continuous zone round the periphery 
of the original drop, but in a series of concentric 7'ings, separated 
by appa^^ently clear zones, the width of which increases with the 
distance from the centre. 

The importance of the phenomenon was immediately perceived 
by R. E. Liesegang, who made it the subject of a very large 
number of experiments of great ingenuity, and who first suggested 
that it supplied the simplest explanation of the formation of a 
natural product, viz., of banded agates. It may be as well to 



22 REPORTS ON THE STATE OF SCIENCE. 1918. 

anticipate somewhat and to indicate at once the reasons for 
attaching importance to what at first sight may appear only a 
curious laboratory experiment. A large number of stratified 
structures occur both in organic and inorganic nature, the explana- 
tion of which has so far generally involved one or more of the 
following assumptions : a periodic supply of either or both 
components of a reaction ; a periodic supply of a catalyst, activating 
or inhibiting agent ; or, finally, a periodic external agency, such 
as, e.g., variations of mean temperature. The Liesegang phenomenon, 
on the other hand, is proof that periodic structures may appear 
where all factors which can possibly exert any influence are 
constant. Where it is applicable as the basis of explanation it 
therefore leads to that economy of assumptions which is the 
desideratum of every hypothesis. 

The conditions of the experiment have been varied by Liesegang 
and subsequent observers. The gel containing one component may 
be allowed to set in a test tube and the solution of the other poured 
on top. Or the gel may fill the bend of a U-tube and two solutions 
may diflFuse into it in opposite directions from the limbs. Finally, 
bodies of gel containing one component may be submerged in 
solutions of the other. The results are substantially the same in all 
cases, although a given reaction may not produce them in an equally 
marked manner with every arrangement. 

The phenomenon has also been studied in gels other than gelatin 
such as agar and silicic acid, and even in porous media of very much 
coarser structure than gels. The nature of the gel, and to a much 
slighter degree its concentration, are now fully proved to have a 
marked specific influence on the result with any given reaction. 
Thus, the reaction between silver nitrate and potassium bichromate 
leads to stratifications in gelatin, but not in agar, while on the other 
hand the reaction between lead nitrate and potassium chromate 
produces them in agar, but not in gelatin, while neither of the two 
leads to a stratified deposit if it takes place in silicic acid gel. A 
great number of reactions have also been investigated, some in all 
three gels and over wide ranges of concentrations, and well marked 
stratifications have been obtained particularly with the following 
precipitates ; lead iodide and lead chromate in agar, lead carbonate 
in agar and in silicic acid, phosphates of the heavy metals in various 
gels, sulphides in various gels and in sand, &c. 

Certain reactions, within wide limits of concentration, do not 
produce stratifications in certain gels. It has, however, been shown 
by Liesegang and by Hatschek — and the point is again of importance 
for the explanation of natural structures — that they can nevertheless 
be obtained as pseudo-morphoses after an intermediate product of 
reaction. Thus Liesegang places a drop of silver nitrate solution on 
a gelatin film containing sodium chloride ; the resulting silver 
chloride forms only a continuous band. If a small fragment of 
potassium bichromate is placed some distance from the edge of the 
drop of silver nitrate, the usual silver chromate strata are formed 
round it when the silver salt has diffused so far, but are promptly 
transformed into silver chloride. The final result is stratifications of 
silver chloride round the site of the bichromate, although such 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 23 

cannot be produced directly. By a slightly different procedure 
Hatschek obtains strata of lead chromate in gelatin, also as pseudo- 
morphoses after silver chromate, although the reaction between lead 
nitrate and potassium chromate in gelatin leads only to a continuous 
band of lead chromate in the ordinary way. 

Microscopic observation of the stratifications, both while in 
course of formation and after completion of the reactions, have been 
made by Liesegang himself and by later investigators. Only in a 
few reactions — of which the original silver chromate one is the best 
example — are the ' clear ' spaces between the rings practically free 
from the insoluble compound : in most cases the rings contain a 
large number of small, and the clear spaces a small number of large, 
crystals or crystalline aggregates. A striking macroscopic illustration 
is afforded by cadmium sulphide in silicic acid gel, which exhibits 
no clear spaces at all, but a continuous succession of alternately 
yellow and pink bands. As is well known, the two shades are due 
to the difference in the size of the particles and both may be obtained 
by precipitating aqueous solutions of different concentrations. It is 
an open question whether, in many cases, the actual amount of 
reaction product in equal volumes of ring and clear space is not 
approximately the same. 

As regards the theory of the phenomenon, the first explanation 
of the origin of periodic deposits was given by Wilhelm Ostwald. 
It is based on the assumption of ' metastable' supersaturation, and is, 
in fact, the principal experimental evidence adduced by him for the 
existence of solutions in that condition. According to him, silver 
chromate is formed as the silver nitrate diffuses into the bichromate- 
gelatin, but at first remains in supersaturated solution until the limit 
of metastability is reacned. When this happens, the silver chromate 
is precipitated and ' on the precipitate thus formed the silver 
chromate, in respect of which the vicinity of the ring is supersaturated 
(the italics are mine, E. H.) is deposited and reinforces it ; this 
continues until the soluble chromate removed from the vicinity has 
gone into the precipitate.' 

H. Bechhold, while generally accepting this theory, has shown 
that it is at least incomplete by demonstrating conclusively that the 
phenomenon is profoundly affected by factors which it fails to take 
into account, such as the solubility of the precipitate in the second 
reaction product, e.g., the solubility of silver chromate in ammonium 
nitrate, ammonium bichromate having been employed in his 
experiments. 

R. E. Liesegang also realised that the experimentum crucis would 
be the failure to produce a second ring system in a layer of gelatin 
already containing one, since the crystals forming the latter should 
obviously prevent supersaturation anywhere in their vicinity. He 
nevertheless succeeded in obtaining such a secondary system, but 
found that it was formed at a level below that of the primary 
stratifications. This result satisfied him that the experiment did not 
refute the supersaturation theory, a conclusion which it is difficult to 
accept. There is no obvious reason why a deposit of silver chromate 
which e.x hy2)othesi (see the italicised passage in the quotation from 
Ostwald) prevents supersaturation radially over some distance 



24 REPORTS ON THE STATE OF SCIENCE. 1918. 

amounting to tnilli metres, should not do so equally at right angles to 
that direction, viz., into the depth of the layer of gelatin. 

E. Hatschek carried out experiments of a more direct character in 
the test tube. Crystalline lead iodide was suspended in agar contain- 
ing also potassium iodide. When lead nitrate solution was allowed, 
to diffuse into this gel, the usual, very perfect stratifications of lead 
iodide were formed, although crystalline nuclei were disseminated 
through the gel and should have made supersaturation impossible. 

R. E. Liesegang does not consider that this result is incompatible 
with the supersaturation theory and suggests that the ' radius of 
action ' of the nuclei is too small to prevent the formation of strata 
which, with the particular reaction, occur at very small distances 
from each other. Without going into any speculations regarding the 
mechanism of this action, it can be said a priori that jLiesegang's 
objection, if j)Valid, would be equally fatal to Ostwald's theory 
itself. 

The reason suggested by Liesegang to prove his own experiment 
inconclusive is, finally, eliminated in a somewhat similar experiment 
bj' L. J. de Whalley (published by E. Hatschek). He obtained a 
second system of stratifications of lead chi'omate in agar, which 
already contained a very fine system of strata of the same compound, 
in a test tube. As the reacting solutions in this arrangement must 
inevitably pass through, and meet in the vicinity of, existing strata, 
the case is different from that of the flat layer used by Liesegang, and 
appears to leave no escape from the conclusion that supersaturation 
was prevented throughout the formation of the second system of 
strata. 

An alternative theory of periodic precipitation has been advanced 
by S. C. Bradford and supported by some experimental evidence, the 
most striking of which consists of photographs of preparations in 
strongly coloured solutions, such as the alkali chromates. Ac3ording 
to him, one of the reacting solutes is adsorbed by the layer of 
precipitate, the result being a zone practically free from it, so that 
the clear space betM'een the strata is at once accounted for. Consider- 
ing the uncertain and conflicting results of adsorption experiments 
with solutions of electrolytes, it would be desirable to support what 
is undoubtedly an attractive suggestion by direct evidence — which 
Bradford so far has not obtained — that the solutes in question are 
actually adsorbed by the appropriate precipitates, e.g., that potassium 
chromate is really adsorbed by lead chromate, or potassium sulphides 
by lead sulphide. 

Apart from the difficulties already set forth, any theory must be 
pronounced inadequate which leaves — as do both Ostwald's and 
Bradford's — the gel out of account altogether. There is an abun- 
dance of material to show that the same reaction, if carried out in 
different gels, leads to entirely different results, in other words, that 
the gel has a specific effect and does not merely act as an indifferent 
medium which prevents mixing or currents. In this connection a 
suggestion made by H. Freundlich incidentally in a paper on 
another subject is of interest : that the formation of periodic strata 
may be an instance of the coagulation by electrolytes of a suspensoid 
sol, While at firgt sight the distinction between a sol of, say, silver 



ON coT.r.oin chemisthy and its industrtat, appi.tcations. 25 

chromate and a ' metastable supersaturated solution ' of the same 
substance may (apart from the fact that we know hardly anything 
definite about the latter type of systems) seem rather subtle, further 
consideration shows that the former assumption immediately 
explains the specific effect of the gel. If electrolyte coagulation is 
the deciding factor, the protective effect of the gel must play an 
important part in promoting or inhiljiting the formation of strata, 
and some such effect is easily traced in the comparative material 
collected principally by E. Hatschek. The consistent differences in 
the results obtained in gelatin, agar, and silicic acid gels point in this 
direction, as the protective effects of the three substances are widely 
different : taking Zsigmondy's ' gold figures ' as measuring this 
property, the protective effect of gelatin and agar is respectively 100 
and 2, while that of silicic acid is negligible. These facts, of course, 
form merely the starting-point for a theory of the Liesegang pheno- 
menon, and a very large amount of work would still be required to 
show its general validity. 

The lack of a general theory of the formation of the Liesegang 
stratifications does not, of course, preclude suggesting a similar origin 
of stratified structures in nature or attempts to reproduce such 
experimentally. Liesegang led the way by explaining the bands in 
agate in this fashion, i.e., by diffusion of iron salts into the 
gelatinous silica from which the stone probably originates, in 
preference to the earlier assumption of alternate deposition. Many 
similar suggestions in regard to both geological and histological 
examples are thrown out in his book entitled ' Geological Diffusions' 
and in his numerous papers. The importance of the phenomenon 
ior botanical anatomy and histology has been insisted on chiefly by 
E. Kuester. Its possible bearing on the transformation of cartilage 
into bone has been pointed out by H. Bechhold, and experimental 
work on this subject should be very fruitful. E. Hatschek and 
A. Simon have shown that a whole series of apparently disconnected 
peculiarities of gold deposits in quartz can be explained by assuming 
the latter to have originally been gelatinous silicic acid, in which the 
reduction of the solutions of gold salts was brought about by one 
of many possible agents. 

In all these directions little more than a beginning has been 
made, and the experimental reproduction and elucidation of natural 
periodic structures should for a long time to come be one of the 
most fruitful fields for applied colloidal chemistry. It seems 
probable that investigation will have to be extended to gels made 
anisotropic by stress, since it is evident that most of the gel-like 
constituents of organisms are in such a condition, at least during 
long periods. 

BiBLIOGnAPHT. 

WiLHELM OSTWALD, Allg. Chemie, 2nd ed., II. 778. 780. 

H. Becchold, The formation of structures in ieWies, /^eltschr. iihyn. C'hem., 52> 
185 (190.5). 

R. E. Liesegang, The imitation of vital processes, Roux's Arch. f. Entwickelu7tgi- 
niechanUi, 33, 328 (1911). 

R. E. Liesegang, Reactions in gelatinous media, /eitschr. f. anal. Chrm., 50, 
82 (1910). 



26 REPORTS ON THE STATE OF SCIENCE. 1918. 

R. E. LlESEGANG, The history of the agates. Aus der Natur, 18, 561 (1911). 

E. Hatschek, The formation of strata in heterogeneous eystems. Koll.-Ztitichr. 
9, 97 (1911). 

R. E. LlESEGANG, Agate Problems, Zentralh. Mineral. Geol. u. Palaeontol., 16, 
497(1911). 

E. Hatschek, A study of some reactions in gels. Journ. Soo. Cherti. Ind., 30i 
255(1911). 

R. E. LlESEGANG, The behaviour of edges and corners in some diffusion ex- 
periments, Eoll.-Zeitschr., 9, 296 (1911). 

E. Hatschek, Reactions in gels and the form and size of the particles of the in- 
soluble product of reaction, Koll.-Zeitschr., 8, 193 (1911). 

R. E. LlESEGANG, Protoplasm structures and their dynamics, Roux's Arch. 
Entwickelungsmech., 34, 452 (1912). 

E. Hatschek, Reactions in silicic acid gels, Koll.-Zeitschr., 9, 11 (1912). 

E. Hatschek, The theory of Liesegang's stratifications, Koll.-Zeitschr., 10, 
124 (1912). 

E. Kuestee, On zone formation in colloidal media, Jena, 1913. 

E. Kuester, Contributions towards the knowledge of Liesegang's rings and 
cognate phenomena, Koll.-Zeitschr., 13, 192 (1913). 

R. E. LlESEGANG, On stratified disperse systems, Koll.-Zeitschr., X^, 1 i &iiA.\^, 
269 (1913). 

E. Hatschek and A. Simon, Gels in relation to ore deposition. Trans. Inst. Min. 
S- Met., 21, 451 (1912). 

E. Hatschek, The theory of Liesegang's stratifications, Koll.-Zeitschr., 14, 
115 (1914). 

R. E. LlESEGANG, Geological diffusions, Leipzig, 1914. 

R. E. LlESEGANG, The action of crystalline nuclei in gels, Koll.-Zeitschr., 16, 
76 (1915). 

R. E. LlESEGANG, Silver chromate rings and spirals, ifei<«cAr.^7iy*. Chem.,QS> 
1 (1914). 

E. KUESTEB, The morphological characteristics of Liesegang's rings, Koll.- 
Zeitschr., 18, 107 (1916). 

F. Koehlee, Rhythmical reactions, Koll.-Zeitschr., 20) 65 (1916). 

S. C. Beadfobd, Adsorptive stratification in gels, Biochem. Journ., 10, 169 
(1916) ; 11, 14 (1917). 

W. MoELLEE, Rhythmical diffusion structures in gelatin-salt jellies, Koll. 
Zeitschr., 19, 209 (1916) ; 20, 242 (1917). 



ELECTRICAL ENDOSMOSE. I. 

By T. R. Briggs, Cornell University. 

1. Electrical Endosmose, Cataphoresis and Allied Phenomena. 

On passing an electric current through a porous diaphragm 
immersed in a liquid, one often observes a flowing of the liquid 
through the diaphragm ; this flow is commonly from the anode to 
cathode, but may take place in the opposite direction. This curious 
phenomenon was described first by Reuss,^ working at Moscow, in 
1808, and to it has been given the name electrical endosmose. Reuss, 
who employed clay diaphragms in water, noticed that, as the current 
forced water through the clay toward the negative pole (cathode), 
there also occurred migration of suspended clay particles in the 
direction of the positive pole (the anode). This migration of 
particles in suspension has come in time to be called cataphoresis, 
and the term should be limited to this meaning. There has arisen, 
however, a great deal of confusion regarding the use of the two 
expressions, electrical endosmose being employed to include 

> Wiedemann, EleUricitdt, \, 1007 (1893). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 27 

• 

cataphoresis,^ and cataphot^esis, on other occasions, being made in 
turn to do double service.' 

Electrokinetic phenomena in two-phase systems of liquid, and 
solid may be analysed into four distinct processes, of which electrical 
endosmose and cataphoresis are the ones commonly met with. So 
far as the electric current is concerned, it is possible to distinguish 
two cases, as follows : — 

(1) A difference of potential sending a current through the system 
may produce a relative displacement of the p?iases. 

(a) If the solid is fixed in the form of a porous diaphragm the 
liquid may be forced through the diaphragm. Electrical endosmose. 

(b) If the solid is in the form of a suspension and is free to move, 
the solid may migrate through the liquid. Cataphoresis. 

(2) A relative displacem,ent of the phases may produce a difference 
of potential and consequently an electric current may flow through 
the system. 

(a) If the solid is fixed in the form of a porous diaphragm 
through which liquid is forced, a difference of potential and an 
electric current may be established between the extremes of the 
diaphragm. Quincke's ' diaphragm current.' 

(6) If the finely divided solid is dropped through the liquid, a 
difference of potential and a current may be set up between the 
upper and lower liquid strata. Billitzer's experiments.* This case 
resembles closely the drop electrode. 

Wiedemann'^ is to be credited with the first quantitative study of 
electrical endosmose, and he was able, as a result, to deduce three 
empirical generalizations : 

(1) The mass of liquid transported in unit time through a porous 
diaphragm, is directly proportional to the strength of the electric 
current ; and, for a given diaphragm material and given current 
strength, it is independent of the length and sectional area of the 
diaphragm. 

(2) The difference in hydrostatic pressure maintained by electrical 
endosmose between the two sides of a porous diaphragm, varies 
directly as the current strength, and for a given diaphragm material 
and a given current, is proportional directly to the length and inversely 
to the sectional area of the diaphragm ; it is also proportional to the 
specific resistance of tlie liquid in the case of an aqueous solution, 

(3) For a given diaphragm material, the difference in hydrostatic 
pressure maintained between the two sides of a porous diaphragm is 
proportional to the applied potential and is independent of the 
dimensions of the diaphragm. 

Quincke^ forced liquid through an apparatus containing a porous 
diaphragm and found that differences of potential were produced. 
He measured these differences and the " diaphragm currents " which 

' Of. Patents of Botho Schwerin (Gesellschaft fiir Elektroosmose). 
3 Cf. Cruse, Phys. Zeif.,6, 201 (1905) : Hittorf ; L'eit.phys. Chem.., 39, 613 (1902); 
43. 239 (1903) ; Morton : Cataphoresis (1898). 

'* Drude's A71h. H, 937 (1903). Cf. Freundlich, Kaj)illarclitmie, 230 (1909). 
■• Pogg-Ann, 87, 321 (18.-j2) ; 99, 177,'(1356). 
^ Pogg.-Ann., 107. 1 (1859) ; HO, 38 (1860). 



28 REPORTS ON THE STATE OF SCIENCE. — 1918. 

• 

resulted and arrived at the following generalization, which may be 
regarded as the converse of Wied?mann's third law : 

" When water is forced at a certain rate through a porous 
diaphragm, the difference of potential produced is independent of the 
dimensions of the diaphragm but is proportional directly to the 
hydrostatic pressure." 

The problem was subsequently taken up by Helmholtz,^ who 
developed quantitatively and mathematically an hypothesis which 
Quincke has previously put forward in a qualitative way. It was 
suggested that, under most circumstances, solids and liquids become 
electrically charged when brought into contact. The distribution of 
charges is such that the surface of the solid is charged oppositely to 
the more or less mobile layer of liquid next it and with which it is 
in contact. This orientation of charges gives rise to a so-called 
electrical double layer, A potential gradient applied externally 
tends to produce a displacement of the electrically charged layer of 
liquid (in case the solid is fixed in the form of a' capillary tube or 
diaphragm) and if the liquid is not a perfect insulator, the displace- 
ment results in a continuous tiow** of liquid along the surface of the 
solid. 

Freundlich,9 following a treatment used by Perrini" has developed 
the following expression for the amount of liquid (Ve) transported in 
unit time through a porous diaphragm : 

v, = a!^ (1) 

" 47r,,l ^"-^ 

In this equation E is the total fall in potential through the 
diaphragm, D and r, are respectively the dielectric constant and the 
viscosity coefficient of the liquid and e is the potential of the 
Quineke-Helmholtz double layer at the solid-liquid interface. Since 
E = RI and R = 1/ yq where R is the total resistance, I is the 
current strength, 1 and q refer respectively to the length and cross 
section of the diaphragm, while y is the specific resistance of the 
liquid, equation (1) may be written 

Ve = Roii2. (2). 

•iTT ^;y 

Since for a given liquid and diaphragm at constant temperature, 
E, r], D and y are constant, V^ is proportional only to the current, 
which flows through the diaphragm and the equation stands in 
agreement with the first of Wiedemann's empirical laws. If one 
calculates the difference of hydrostatic pressure P,, produced by 
electrical endosmose equation (3) is the result : 

Pe = /32£ED (3). 

where i3 is inversely proportional to the size of the pores in the 
diaphragm. D, e, and /3 being constant for a given diaphragm and 
liquid at constant temperature, equation (3) is a mathematical state- 
ment of Wiedemann's third law.'i 

' Wied. Ann., 7, 337 (1879) et. seq. 

" Cf. Lamb, Phil. Mag., (.5) 25. r,2 (1888). 

'■• Ka/MIarc/if^mit; 22.5 (1909) ; Cf. Brings : Jour. I'hiis. Chem. 91 (1917). 

" Jour. Chim.. Phifs., 1904. *-i v ^ 

>i Cf. Quinoke, Pogg Ann., 113, 513 (1861). 



ON COJJ.OIU CIIKillSTRY AND ITS INDUSTHIAJ. A PIM.I CATIONS. 29 

2. Electrical Endusmose ivith Pure Liquids, Coehn's Rule. 

The early experiments on f lectrical end osmose taken in conjunc- 
tion with those on the migration of suspended particles (cataphoresis) 
made it appear that solids were charged negatively in contact with 
water. When turpentine was used instead of water, however, 
Quincke found that conditions were reversed and that such solids as 
quartz, shellac, silk, clay, asbestos, porcelain, ivory shavings, animal 
membranes, &c., were electropositive, with the single exception of 
sulphur. Sulphur weakly electronegative against turpentine, against 
water was the most strongly electronegative of all ihe solids which 
Quincke studied. 

Coehn^^ j^^g considered the question raised by these differences, 
and has proposed the following empirical rule : 

When two non-miscihle substances, one of ivhich is a pure liquid, 
are in contact, the -suhstance with the higher dielectric constant is 
positive against the suhstance with the lower. 

Quincke's data appear intelligible in the light of Coehn's rule. 
Water and turpentine have dielectric constants of 81 and 5, respec- 
tively. Furthermore, the constant in the case of water is one of the 
largest known and we should expect nearly every substance to be 
electronegative against water. In contact with turpentine, however, 
many substances ought to be electropositive, exactly as Quincke 
found was the case experimentally. Coehn's rule appears to hold 
fairly well for pure liquids (although there are some weak points in 
his own evidence)!^, but when applied to aqueous solutions, 
especially those containing dissolved electrolytes, the rule fails 
utterly. 

3. Electrical Endosmose with Solutions. Effect of Acids, Bases 
and Salts. 

In all the early experiments, as we have seen in the preceding 
sections, water flowed to the cathode. Not only pure water showed 
this unidirectional tendency, but aqueous solutions appeared to do so 
as well, the only difference being that the rate of flow was less for 
solutions than for the pure solvent.^* Consequently, after the 
acceptance of the physical theory of the electrical double layer, the 
belief became general that all solids were charged negatively by 
contact either with water or with aqueous solutions. 

Nevertheless, instances^^ had been recorded where aqueous 
solutions flowed to the anode rather than towards the cathode. 
Hittorf"^ found, for instance, that cadmium chloride solutions Howed 
to the anode through animal membrane but went to the cathode 
through earthenware, and although Perrin is usually credited with 
the first definite statement that " reversals " to the anode were possible 
and could be produced at will by suitable choice of electrolyte in 

'2 Wied. Ann., 64. 227 (1898), Zeit. EleUrooliemie, 16, 586 (1910). 
•3 Cf. Briggs. Jour Plnj.'<. Chcm., 21, 204 (1917). 

•« Porrett. Thonigon'f Aniiah of Philo.wphy, 8, 74 (1816): Daniell, Pint 
Trails:, 129, 97 (1839 ~) ; Gernez, (omptex rendiig, 89, :i03, 348 (1879). 

'•• Wiedemann. KleMrhntat, 2, l^:? (1883) ; Gore, Proc. Jtoy. Sue. 31, 2ri3 (1880) 
'« /eif. Phys. Chem. 39 613 (1902) ; 43, 239 (1903). 



30 REPORTS ON THE STATE OF SCIENCE. 1918. 

solution, the point was really established with remarkable clearness 
by Parker.i'^ 

Perrin's contributioni*^ to what was still an obscure phenomenon, 
did, however, constitute a great step forward. He devised an 
apparatus which enabled him to employ many different powdered 
substances in the form of pervious diaphragms. Turning his atten- 
tion to the effect of dissolved substances and using extremely dilute 
solutions (never more concentrated than N/50 and usually about 
N/500), he concluded first that electrolytes alone among solutes 
influenced the course of electrical endosmose and that the ions had 
a specific effect. Hydrogen and hydroxy 1 ions proved particularly 
active. With a diaphragm of insoluble chromic chloride, for example, 
dilute alkalies flowed to the cathode whilst dilute acids flowed to the 
anode — a clear cut reversal. Similar acid alkali reversals were found 
with alumina, carborundum, sulphur, gelatine, graphite, naphthalene, 
etc., although none was observed with cotton wool, glass and 
iodoform. Whenever reversal did occur, there was a certain 
hydrogen ion concentration at which no flow at all occurred, this 
point corresponding approximately to an isoelectric condition of the 
diaphragm. 18 

Since flow to the cathode indicated an electronegative diaphragm, 
whilst flow to the anode pointed to an electropositive one, Perrin 
concluded as follows : — 

' The electric potential of any surface whatever in aqueous 
solution is invariably increased [made more positive or less negative] 
by the addition of a monobasic acid and is invariably lowered 
[made more negative or less positive] by the addition of a non- 
acid base.' 

Perrin considered next a large number of other ions. He found 
that, excepting hydrogen and hydroxyl, none of the common 
univalent ions was of much influence on electrical endosmose. 
Polyvalent ions were more active. Briefly, the results may be sum- 
marized in the following statement, sometimes referred to as 
Perrin's valence rule, which one should compare with the Schulze- 
Hardy rule of flocculation : 

Every diaphragm tends to hecome charged positively in an acid 
solution and negatively in an alkaline one. Every ion of unlike 
sign tends to neutralize the charge on the diaphragm and this 
tendency increctses rapidly with the valence. 

Perrin's rule has been extended to alcoholic solutions' by 
Baudouin^o, incompletely to liquid ammonia by Ascoli^^ and by 
Guillaume^^ to the so-called Bose-Guillaume phenomenon. 

Morse and Horn^^ have made use of electrical endosmose to 
remove air from the pores of porous cups, before impregnating the 

1' Johns HopMm Dissertatiom, 31, 23 (1901) ; Cf. Briggs, Jour. Phys. Chem. 
21, 235 (1917). 

'8 Jour. Chim. Phys. 2, 601 (1904). 

»9 Cf., however, Bethe and Toropoff, Zeif. Phys. Chem. 89. ^97 (1915). 

'» Comptes rendiis, 138, 898 (1904). 

*' Comptes rendiis, 137, 1253 (19"3). 

22 JUd. 147, 53(1908) ; Cf. Brings : Jour. Phys. Chem. 21- 215 (1917). 

23 Amer. Chem. Jour., 26. 801 (1901). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 31 

latter with copper ferrocyanide. This led Frazer and Holmes^* to 
carry out experiments with an elaborate electro-osmometer, in which 
they noticed the usual acid-alkali reversals and concluded that the 
effect of the ions bore some relation to their migration velocities. 
Coehn^^ has also carried out some interesting electro osmotic 
measurements with a Pukall filter and solutions of H2SO4, CUSO4, 
HNO3, acetic acid, alkali metal sulphates, alkali and heavy metal 
nitrates. 

Barratt and Harris^'^ in some excellent work with diaphragms of 
gelatine, agar and parchment, have confirmed in the main the valence 
rule of Perrin. Their data suggest the problem of finding out what 
effect the salts of Hofmeister's series would have on endosmose 
through gelatine and other albumenoids. Recently this question has 
been investigated by Bethe and Toropoff-'' and although the data are 
incomplete, there is reason to believe that the lyotrope serif^s really 
does play an important part. 

An elaborate study of electric endosmose in neutral solutions has 
been completed bj' Elissafoff-'* in Freundlich's laboratory. The pro- 
cedure was based on Lemstrom's'^^ method of measuring endosmetic 
movements in a single capillary without the direct application of 
electrodes. Elissafoff's data show that Perrin's valence rule holds only 
to a limited extent. So far as the alkali metal and alkaline earth metal 
cations are concerned the valency rule holds satisfactorily,^'* but fails 
in the case of heavy metal and organic cations. For example, certain 
univalent organic cations appeared quite as effective in neutralizing 
the charge (see the second part of Perrin's rule) on negative glass or 
quartz as did the divalent light metal cations. Silver as ion belonged 
to the divalent metals ; mercuric chloride was as effective as 
aluminum sulphate and far more so than chlorides of the divalent 
alkaline earths. That the anion is also active v>a3 demonstrated by 
experiments with potassium benzoate and sodium picrate, these 
anions restraining the tendency of the potassium or sodium to 
neutralize the negative charge on the walls of the capillary. 

No reversal by acids was observed, but the strength of the 
solutions employed was never greater than one ten-thousandth 
normal. With certain salts, however, reversals were obtained. 
Against solutions of thorium nitrate of sufficiently high concentra- 
tion the glass or quartz became electropositive and a similar reversal 
occurred with solutions of methyl violet, a basic dye. One should 
compare this with what Larguier des Bancels^^ found with wool and 
basis dyes, where the latter showed a striking tendency to make the 
wool positive. 

" Aw.er. Chem. Joiir., 40, 319 (1908) ; H. N. Holmes, Dissertation {Johns 
Hopkins, 1907). 

2^ Zeit. EleUrochemii', 16, 586 (1910). 

26 Zeit. Elektrochemie, 18, 221 (1912) ; Biochemical Jour., 6, 315 (1912). 

2' Loc. cit. 

'8 Zeit. Phys. Chem., 79, 385 (1912). 

-'3 Bnide's Aim., 5, 729 (1901). 

3" Freundlich and Elissafoff have employed electro-osmosis to estimate the 
valency of radium. The results agree with the assumption that radium is a 
divalent metal belonging to the alkaline earth group. Phi/K. Zeit., 14, 1052 (1913). 

'' Compter rendiu. 149, 310 (1909). 



82 REPORTS ON THE STATE OF SCIENCE. 1918. 

4. Theories of Electrical Endosmose. Contact Electrification ay id 
Adsorption. 

Wiedemann believed that the electric current exerted a tractive 
action upon the liquid in a capillary tube and that the liquid was 
carried thus from anode to cathode, regardless of the substance 
composing the walls. In opposition to this view, Graham,^- Quintus 
Icilius and Breda and Logemann,^^ showed conclusively that no 
transport of liquid occurred unless a diaphragm or its equivalent 
were present. As I observed in the earlier pages of this paper, we 
owe to Quincke and to Helmholtz the electrical double layer theory 
of contact electrification. The Coehn rule is an interesting develop- 
ment of this theory. But both Quincke and Helmholtz contributed 
little to further our understanding of why and how an electrical 
double layer or its equivalent may be formed when solid and liquid 
are placed in contact. 

For the special case of a metal in contact with its own ions in 
solution the Nernst theory holds. It is only natural that there 
should have been proposed an analogous explanation of the contact 
potentials of non-metallic solids. Every solid dissolves in water to a 
certain extent and the electrical double layer might be supposed to 
be produced by differences in the rates of ion diffusion — if the 
cation diflFused faster, a separation of charges would tend to occur 
and the solid (or liquid immediately in contact with the solid) 
would become negative. Bredig^* has given vague expression to 
this idea by observing that the Coehn rule points to some relation 
between the solubility of ions in diflPerent media and the dielectric 
constant. 

As a matter of fact, the explanation outlined above cannot be the 
correct one for the case of a solid immersed in a pure liquid, unless 
one postulates that the liquid remains unsaturated with respect to 
the solid or that fresh liquid is being supi^lied constantly. The 
electrical charge does not disappear when the liquid is saturated with 
the particular solid, although its sign and intensity may change, 
while the potential difference at the liquid interface in a concentration 
cell exists only so long as a difference in concentration is maintained. 
No permanent potential difference can possibly be produced as the 
result of unequal ion mobilities. Perrin has offered an explanation 
of his acid-alkali rule by postulating that, since hydrogen and 
hydroxyl ions are abnormally mobile, they are correspondingly small, 
and are able thereby to crowd to the surface of a solid more closely 
than the other ions. This might account for the solid being positive 
in acid and negative in alkaline solutions. Perrin was unable, 
nevertheless, to reconcile his theory with all the facts, for he 
observed that lithium bromide failed to charge a chromic chloride 
diaphragm negatively although bromine ions are twice as mobile as 
lithium ions. 

Haber^^ has suggested for the particular case of glass against 
water that the solid is essentially a hydrogen electrode, and that the 

32 (2) Phil. 3Iag. (4) 8, 151 (1854). 

« (3) Pogg. Ann., 100, 149 (1857). 

3< Zeit. Mektrochemie, Q, 7.38 (1903). 

'5 Ilabe?- and Meniensiewicz, Zeit. Phijs. Chem., 67- 413 (1909). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 33 

magnitude of the potential difference depends upon the concentration 
of hydrogen ions in solution. Guided by Haber's theory, Cameron 
and Oettinger-"' performed some rather inconclusive experiments on 
the potential produced by acid and alkaline solutions forced through 
a capillary of glass. Habers theory, as Freundlich points out, is 
open to the serious objection that electrical endosmose does not 
depend entirely upon hydrolysis of the dissolved solute, as it should 
do if thf concentration of hydrogen ions is the only factor. Acidity 
and alkalinity, while of very great influence, are not the only factor 
Jetermining electro-osmotic effects. 

Freundlich.^' was the first to point out clearly the intimate 
relations existing between adsorption and electrical endosmose. 
This development may be said to be the result of his own work on 
adsorption and the speculation of Perrin^** regarding the analogies 
between the behaviour of suspensions and the peculiarities of 
electrical endosmose. Freundlich went still further than Perrin. 
He had already shown the relation between adsorption and ihe 
stability of suspensions and had pointed out the validity of the 
Schulze valence rule for adsorbed light-metal caticns and the 
ordinary anions. He had discovered, too, that many organic ions as 
well as the heavy metal cations were exceptions to the Schulze rule. 
He was able, as a result, to emphasize the similarity between the 
Schulze rule and the valence rule of Perrin, and. from Klissafoffi's 
data, he showed that exceptions to Schulzc's rule were exceptions 
likewise to Perrin's. From this it was only a step forward to 
apply to electro-osmotic phenomena a definite theory based upon 
adsorption, or more specifically, upon the selective or preferential 
adsorption of ions. 

Freundlich called the difference of potential between solid and 
solution, the "ad?orption potential." If a cation is adsorbed to a 
greater extent than the accompanying anion, the solid becomes 
positively charged, and if it is employed as a diaphragm, the 
electrical endosmose will occur from cathode to anode. For the case 
of a solid against pure water it is only necessary to postulate 
selective adsorption, either of the ions already present in water or 
produced by the solid dissolving. When preferential ion adsorption 
occurs, the number of ions actually adsorbed is very small, because 
the charge on a single ion is relatively large and the electrical double 
layer that is established opposes any further spatial separation of 
positive and negative ions. 

Freundlich^^ has recently modified his original theory of the 
the adsorption potential, without improving matters appreciably and 
not without adding several complicating hypotheses. He suggests 
that the contact potential of the diaphragm depends upon the nature 
of the material of which it is composed (upon differences in solution 
tension of the ions thrown out) and that it is affected only indirectly 
by adsorption. In my opinion contact potential does undoubtedly 
depend upon the nature of the solid itself, but the important thing 

36 Phil. Mag. (6), 18, 586 (1909). 

" Kapillarchemie, 245 (1909) ; Zeif. Phijs. Cfiem. 79, 407 (1912). 

38 Jour. Chim. Pliy.t., 3, 85. (1905). 

3» Freundlich and Elissafoff, Zeit. Phys. Chem., 79, 407 (1912). 

20895 B 



34 REPORTS ON THE STATE OF SCIENCE.— 1918. 

is the power of the solid to adsorb selectively the ions present in the 
liquid from the beginning, or prodnced by the solid dissolving.^'' 

Frazer and Holmes'*\ following a suggestion rejected by Whetham,^^ 
have advanced a distinctly different hypothesis based upon the 
solvate theory. If the hydration of the cation is greater than that 
of the anion, for example, liquid shoidd be carried from anode to 
cathode ; and this is what the authors found to be the case with 
neutral salts of the alkalies against earthenware. Since the mobility 
of an ion might be regarded as an inverse measure of its hydration, 
one could expect a strong flow to the cathode in an alkaline solution 
and a strong flow to the anode in an acid solution. This deduction 
agreed with the facts as far as they were determined by Frazer and 
Holmes. Barratt and Harris, who favoured a similar theory, were 
rather overwhelmed by its consequences, for they calculated that 
anywhere between 18 and 370 molecules of water were transported 
through agar diaphragms for every molecule of solute decomposed 
electrolytically.*^ 

The solvate theory of Frazer and Holmes cannot be correct, for 
one would have to conclude, in consequence, that there is a funda- 
mental difference between electrical endosmose and Quincke's dia- 
phragm currents. Moreover the theory assigns to the diaphragm a 
subordinate and purely mechanical role. Neither does it explain 
why mei-e traces of lanthanum salts, for instance, reduce the flow 
of an alkaline solution, or why an acid solution ^oz^;s to the cathode 
through powdered glass. If there is any relation between endosmose 
and ion mobility, it is better to consider it an indirect one, produced 
by a possible relation between ion mobility and ion adsorption, as I 
pointed out when discussing Perrin's speculations. 

After careful consideration of the facts in the case, it would 
appear that the most satisfactory working hypothesis to account for 
contact electrification of this type (and hence to serve as basis to an 
understanding of electrical endosmose and cataphoresis) is the one 
proposed originally by Freundlich and emphasized recently by 
Bancroft.^ 

By virtue of their surface properties solids are able to adsorb 
substances from a liquid with which they are in contact. They may 
adsorb a particular ion preferentially, in which case we have selective 
ioD adsorption and either a positive or negative charge on the solid. 
The adsorbing substance tends to be peptized by the adsorbed ion. 

*" The modified Freundlich. theory of the ionization of colloid aj^gregates, 
according to which particles of a basic nature, such as ferric hydroxide, are believed 
to give off OH ions to the liquid and become positively charged, while particles of 
acid nature, such as silica, give up H ions to the liquid and become electro-negative. 
The suggestion has received the support of Zsigmondy and many others. While it 
is easy thus to account for the charge borne by substances such as silica and ferric 
hydroxide, it is by no means so simple to do so with substances such as sulphur, 
carborundum, and diamond, all of which are charged electrically when placed in 
contact with water or suitable aqueous solutions. Compare Burton, The Physical 
Properties of Colloid Solutions (1916). 

« Am. Chem. Jour., 40, 319 (1908). 

« Theory of Solution, 292 (1902). 

^5 In connection with Frazer and Holmes' theory, see Bethe and Toropoff, Zeit. 
Phys. Chem., 89, 597 (1915). 

" Jour. Phys. Chem., 16, 312 (1912); Trans. Am. JElectrochem. Soc, 21, 233 (1913). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 35 

Or solid maj- adsorb the solvent itself and be peptized, while the 
other possibilities, all of which tend to produce peptization, are 
adsorption of a non-electrolj'te, an indissociated salt, or a second 
colloid.*^ Since electrical endosmowe has to do with electrically 
charged surfaces, we are concerned chiefly with preferential adsorp- 
tion of ions. 

It is necessary to postulate that every solid has a specific adsorbing 
power for a given ion, depending upon the specific surface'® of the 
solid, upon the temperature, upon the concentration of the particular 
ion in the solution and upon the other ions present, or adsorbed 
previously by the solid. When the ion content of a liquid is 
vanishingly small, we shall have but little ion adsorption and little 
electrical endosmose. On the other hand ' pure ' water shows 
marked endosmose through many diaphragms. This is a case of 
preferential ion adsorption where the irons are produced both from 
the ionization of water itself and the solution of the solid, which is 
a very important matter in some cases (notably glass).*^ Since the 
majority of solids are charged negatively against water, hydroxyl 
ions are probably adsorbed in preference to hydrogen ions. In 
discussing the potential of a solid against water originally pure, we 
must accordingly take two factors into account.''** 

(1) The specific adsorption capacity of the solid for hydrogen 
and hydroxyl ions produced by the dissociation of water. 

(2) The dissolution of the solid, which, though extremely slight 
in many cases, may produce ions that are strongly adsorbed. 

Hydrogen ions are often adsorbed preferentially from solutions 
containing them, especially from acids, though we have seen that the 
rule is by no means a general one. Experiments by the author have 
shown that aluminum, which is positive in dilute hydrochloric acid, 
is weakly negative in citrate acid where the equivalent selective 
adsorption of the citrate ion must be greater than that of the hydrogen 
ion. Moreover, we know that metal sulphides are peptized by 
hydrogen sulphide, an acid, yet the adsorbed ion is sulphur and not 
hydrogen ; for the particles in suspension are electro-negative.''^ 

In general the same statement applies to the adsorption of 
hydroxyl ions. Solids seem to have a somewhat greater adsorption 
affinity for hydroxyl ions than for hydrogen ions, though there are 
notable exceptions to this generalization. The general theory cover- 
ing the electrical endosmose of all liquids and solutions may be 
formulated as follows : — 

(1) Electrical endosmose depends upon the preferential or selec- 
tive adsorption of ions and is inttuenced only by those ions which 
are adsorbed by the diaphragm. 

« Cl:. Bancroft, Jour. Phys. C'ltem., 20. 85 (1916). 

« Wo. Ostwald, Grundrins dcr Kolloidchemie, 29 (1912).] 

" Cf. Briggs, Bennett, and Pierson, Juxu: Phyx. C/iein., 22, 256 (1918) ; Trans. 
Am. Electrucheiu. Sue, 31, ^57 (1917). 

*" In this connection, compare the statement of Schwerin, Brit. Pat. 10793 (1909) 
wherein he emphasises the importance of taking into account the dissolving of the 
diaphragm. 

■"* Winssinger, Bull. Soc. chem., Paris (3), 49, 452 (1888) ; Linder and Picton, Jo^r. 
Chem. Sue, 61, 116 (1892), 

In this connection compare the beautiful experiments of Lottermoser, Jour, 
prakt. Chem. (2), 72. ^3 (1905). 

20895 B 2 



36 REPORTS ON THE STATE OF SCIENCE. — 1918. 

(2) Any circumstance or condition which changes the adsorption 
produces an effect upon electrical endosmose. Electrical endosmose 
varies, therefore, with the condition of the surface (for a given solid), 
with the relative and absolute ion concentrations, with the tempera- 
ture and so forth. 

(3) The direction of endosmose indicates the sign of the dia- 
phragm ; the rate of endosmose is proportional to the intensity of 
the charge on the diaphragm in case the potential gradient through 
the diaphragm is constant. When the liquid flows to the cathode, 
the diaphragm is negative ; when it flows to the anode the dia- 
phragm is positive. No flow at all probably indicates an iso-electric 
condition.^" 

(4) A diaphragm tends to become positive by the selective adsorp- 
tion of cations, and negative by the adsorption of anions. 

(5) The positive charge produced by an adsorbed cation is neutral- 
ized more or less by the addition of an adsorbed anion, the effect 
increasing with the concentration of the anion. Similarly, the 
negative charge produced by an anion is neutralized by an adsorbed 
cation. 

(6) Electrical endosmose measures the tendency of a solid to 
form an electrical suspension in a given liquid, but it does not 
measure the tendency of the solid to form a non-electrical suspen- 
sion, such as is produced by adsorbed solvent, solute or neutral 
colloid.^^ 

5. Adsorjjtion Potential, Temperature and other Factors. 

Returning to equation 1 it is hardly necessary to point out that t, 
representing the potential of the Quincke-Helmholtz double layer, 
stands also for the ' adsorption potential ' of the solid-liquid interface. 
Quincke and also Von Tereschin have calculated values'^ of e for a 
glass-water interface, using data obtained by electro-osmotic experi- 
ments with capillary tubes. The values lie close to 50 millivolts and 
are of the same order of magnitude as those^* calculated from the 
migration velocities of particles suspended in water (cataphoresis). 

From the beginning it has been recognized that electrical en- 
dosmose is greatly affected by changes of temperature. Perrin found 
that, with rising temperature, the volume of liquid transported under 
otherwise constant conditions increased very rapidly, and he reported 
that temperature had ahout the same effect on the rate of endosmose as 
it had on tliefiuidity (recijjrocal of viscosity) of the liquid. Equation 
1 indicates that this condition is plausible (since D does not change 
rapidly with the temperature), provided £ remains practically con- 
stant as the temperature changes. Perrin's conclusion that the 

5" Note that Bethe and Toropoff maintain that the ' indifiEerent ' point (zero flow) 
and the isoelectric point do not necessarily coincide exactly. Zeit. Phys. Chem. 89, 
597 (1915). 

*' Schwerin has applied this principle in Brit. Pat. 2379 (1911), where in order to 
obtain stable suspensions he adds acids to those substances which migrate to the 
cathode and bases to those which migrate to the anode. In 27930 (1911) he adds 
adsorbed positive or negative colloids (alumina, humic acid, silica, etc.) to obtain the 
same results. 

"3 Freundlich, Kapillarchemie, 227 (1909). 

=- Data compiled by Burton, Phijdcal Properties of Colloid Solutions, 135 (1916). 



OS COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 37 

temperature coefficient of viscosity determines very largely the 
value of the temperature coefficient of electro-osmose, is strenerthened 
by experiments of Coehn and Raydt,-'» Cameron and Oettingerj's* and 
of Briggs, Bennett and Pierson.'^s 

On the other hand Cruse" found an apparent maximum in the 
rate of electro-osmose, this maximum occurring between 35° and 
40° C. Briggs, Bennett, and Pierson have shown that Cruse's 
maximum was probably due to the diaphragm not being in equi- 
librium with the liquid phase. They have carried out determination 
of the temperature coefficient and find that with diaphragms of 
asbestos, cellulose (filter paper) and carborundum, the rate of flow 
increases with rising temperature slightly less rapidly than the 
viscosity decreases ; the rate for a given diaphragm at constant 
temperature is also very exactly proportional to the applied external 
potential. It is only fair to point out, however, that since adsorption 
varies with the temperature, and since the temperature coefficients for 
anion and cation are not necessarily equal, « may also vary with the 
temperature and might even change its sign. In the cases just 
discussed, e is probably very nearly constant. 

6. Belated Phenomena. — Cataphoresis is the reverse of electrical 
endosmose. One is dealing here with a mobile or "floating" dia- 
phragm. The fundamental theory is without question the same ; 
such differences as appear to exist between the two processes being 
due, in all likelihood, to flocculation complicating the phenomena of 
cataphoresis. The particles are positive if they migrate to the cathode, 
negative if they migrate to the anode. Acid-alkali reversals are 
known, and strongly adsorbed ions determine the charge on the 
particles. As the subject constitutes a separate report in this series, 
it will not be considered further at this time. 

Perrin^s has pointed out that the curious Bose-Guillaume phe- 
nomena is a special case of Quincke's " diaphragm currents," and is an 
electro-osmotic phenomenon. Guillaume's data'*''^ are evidence in 
favour of the adsorption theory. Electro-stenolysis is another phe- 
nomenon dependent upon contact electrification. 

When certain aqueous solutions are separated from water by a 
porous plate of porcelain, for instance, a slight but measurable osmosis 
Is often observed. In some instances the osmotic flow occurs from 
the solution into the water and not from the water into the solution 
as one would expect it to do. Such apparently abnormal osmosis is 
termed " negative osmose."^'^ 

According to Bartell the most plausible way of accounting for 
osmosis of this type is to assume that it is caused by the " polar- 
ization " of the membrane. The membrane being in contact with 
different liquids, the adsorption potential will be different for each 

•■*< Drnde'g Ann., 30, 797 (1909). 

'^ Phil. Mag. (6) 18, 586 (1909). 

56 Juui: Phys. Chem. 22, 256 (1918). 

" Phyx. Ztit., 6, 201 (ly05). 

•^» Cowptes reudiis, 147, 55 (1908). 

■^^ IbUl. 147. 53 (1908). 

'^>' Bartell, Jour. Am. Chem, Soc. 36. 646 (1914) ; Bartell and Hocker, Jour. Am. 
Chem. Soc, 38. 1029 (1916) ; Freundliuli, Zeit. Kolloidchcm ie. 18, 11 (1916) ; Girard 
CWy^te m((/«.v, 146, 927 (1908) ; 151, 99 (1910) e^ .vfy . ' 

20895 B 3 



38 REPORTS ON THE STATE OF SCIENCE. 1918. 

face and there will be established a difference of potential between 
the ends of the capillaries. This difference in potential causes 
electrical endosmose to take place in one direction or the other and 
an apparent osmotic action results. That a difference of potential 
really does exist between the water side and the solution side of the 
diaphragm has been demonstrated experimentally. The explanation 
outlined above is an ingenious one, but the problem is by no means 
solved as yet.*^ 

Summary. 

Electro-osmotic phenomena with pure liquids and solutions have 
been described and the various theories discussed critically. The 
most plausible hypothesis seems to be the Freundlich-Bancroft 
theory of selective ion adsorption. The effect of temperature 
changes and other influences have been considered and in conclusion 
mention has been made of negative osmosis and other phenomena 
related closely to electrical endosmose. Cataphoresis and electro- 
stenolysis have not been included. 



Recent Papers on Electeical Endosmose. 

' Electric osmosis and concentration of electrolytes.' J. 0. Wakelin Baeeatt and 
Albert B. Harris, Zeit. Ehhtrochemie, 18, 221 (1912). 

Authors have studied electrical endosmose through diaphragms of gelatin, 
parchment and agar. Rate of flow and direction of osmose appear to be determined 
by the nature and valence of the ions in solution. See next reference for more 
comprehensive article. 

' Electro-osmosis.' J. 0. Wakelin Barratt and Albert B. Harris. Biochemical 
Jour., 6, 31.5 (1916). 

See preceding reference. Article gives data for a large number of diaphragm 
substances, describes ingenious apparatus and discusses the hydration theory. 
Electro-osmose into human forearm studied. 

' The effect of electrolytes on electrical endosmose.' G. von EL:ssAt'0FF. Zeit. 
Phys. Chem., 79, 3S.5 (1912). 
Very important article showing where Perrin's valence rule holds and where it 
fails. In an appendix written with Freundlich, the author argues very effectually 
in favour of the ionic adsorption theory. 

'Electrical endosmose.' Wilder D. Bancroft, Jovr. Phyg. Chem., 16, 312 (1912) ; 
Trans. Am. Electruchem. Soc, 21, 233 (1912). 
Proposes ionic adsorption hypothesis and applies it to some hitherto unexplained 
experiments of Reed, Traits. Am. Electrochem. Soc, 2, 238 (1902). Article includes 
discussion of addition agents in electroplating. 

'Determination of the valence of radium by means of electrical endosmose.' 
Herbert Freundlich and G. von Elissafofp, Phys. Zeit., 14. 1052 (1913). 
Radium appears to be divalent and closely related to barium. Method depends 
upon application of Perrin's rule and requires less than O'Ol milligram of 
substance. 

' Hydration of organic colloids under the influence of electrolysis.' E. Doumek, 
Comytes reiulus Soc. Biol., 76, 10 (1914). 
Some curious hydration and dehydration effects observed during electrical 
endosmose with gelatin. 

' Negative osmose.' F. E. Baetell. Jour. Am. Chem. Soc, 36; 646 (1914). 

Author accounts for positive and negative osmosis through porcelain by assuming 
that selective adsorption polarises the membrane and that the osmosis is really 
electrical endosmose. 

61 Cf. Bancroft, Jonr. Phys. Chem., 21, 441 (1917). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 39 

' Electrolytic endosmose.' Horace G. Bters and Carl H. Walter, Jour. Am. 
Chem. Soo. 36, 2284 (1914). 
Complicated endosmotic experiments with three and six compartment cells. 

' Electrolytic processes of diaphragms.' I. Disturbance of Neutrality. Albrecht 
Bethe and T. Toropoff, Zeit. Phy.t. Chnn. 88. "SB (1914). 
With organic diaphragms electro-osmoso causes H* concentration to decrease at 
anode side and increase at the cathode side. Electrolytes in solution affect the speed 
with which the neutrality is disturbed. The order of anions and cations recalls the 
Hofmeister series. 

' Electrolytic processes at diaphragms.' II. The dependence of the magnitude and 
direction of the concentration changes and t'ne water movement upon the hydro- 
gen ion concentration. A. Bethe and T. Toropoff, Zeit. Phys. Chem., 89, 637 
(191.5). 
Article includes a number of experiments on electrical endosmose with gelatin, 

albumin, collodion, animal and other membranes. Interface potential is an ionic 

adsorption phenomenon ; electrical endosmose depends both upon interface potential 

and the relative hydration of mobile ions. 

' The relation of osmose of solutions of electrolytes to membrane potentials.' Theo- 
retical. 1'. E. Barker and C. D. Hooker, Jour. Am. Chem. Soc, 38, 1029 
(1916). 
Author combines ionic adsorption theory with Nernst diffusion theory to account 

for polarization of membrane. 

' The osmose of some solutions of electrolytes with porcelain membranes and the 
relation of osmose to membrane potential.' F. E. Bartell and C. D. Hooker, 
Jour. Am. Chem.. Soc, 38, 1036 (1916). 

' Negative osmosis.' Herbert Freundlich, Zeit. Kolloidchemie, 18, 11 (1916). 
(Original article not available.) 

1917. 

' Electrical endosmose,' I. T. R. Briggs, Jour. Phys. Chrm., 21, 198 (1917). 

Complete historical summary with references to literature. Critical study of 
different theories of electro-osmose and contact potentials. Author prefers ionic 
adsorption hypothesis of Freundlich and Bancroft. 

• Electrical endosmose and adsorption.' T. R. Briggs, H. L. Pierson, and H. S. 
Bennett, Trans. Am. Electroohem.. Soc, 31, 257 (1917). 
See below. 

1918. 

Electrical endosmose,' II. T. R. Briggs, H. S. Bennett, and H. L. Pierson, 
Jouv. Phys. Chem.., 22- 256 (1918). 

Authors describe new and convenient electro-osmometer and study the relation 
between the rate of endosmose and voltage, temperature and other factors. Data 
tend to confirm ionic adsorption theory. 

ELECTRICAL ENDOSMOSE. IL INDUSTRIAL APPLICATIONS. 

By T. R. Briggs, Cornell University. 

Introduction. 

During recent years increasing attention lias been paid to the 
possibility of making some practical application of electro-kinetic 
processes, inclnding electrical endosmose.^ It is proposed in this 
report to indicate to what extent and in what direction these in- 
dustrial applications have been attempted and to elucidate, wherever 
necessary and whenever possible, the principles involved. Owing 

1 Cf Foerster : EleUrochemie, 116 (1915); Kruyt : Chem. WerhhJail 14, 766(1917); 
Chem. Abstr., 11, 2984 (1917) ; Lewis : Jour. Soc Chem. Ind.. 35, 575 (1916). 

20895 ^ ■* 



40 REPORTS OK^ THE STATE OF SCIENCE. — 1918. 

to the close relationship existing between electrical endosmose and 
cataphoresis and because of the not very surprising fact that cata- 
phoresis plays a very important part in many so-called "electro- 
osmotic" processes in practice, no attempt will be made to exclude 
technical cataphoresis from this discussion or to limit it strictly to 
electrical endosmose. 

Dewatering Peat by Electrical Endosmose. 

The possibility of using electrical endosmose and cataphoresis in 
the removal of water from muds, pulps and jelly-like or spongy masses 
containing materials in suspension, has been considered in some 
detail during recent years, especially by Count Botho Schwerin in 
Germany. The peat bogs of the latter country and of Ireland offer 
a very great potential source of fuel provided only a sufficiently 
economical method can be devised for dewatering the material. 
Filtration and centrifuging are not applicable because of the slimy 
nature of the peat pulp, which causes an impervious layer to form 
on the filter or in the centrifuge. Attempts have been made to sub- 
mit the peat mud to stream evaporation combined with drying in the 
air. The mud as it comes from the bog contains approximately 90 
per cent, of water and to evaporate a pound of this material con- 
taining 50 per cent, of water (which can then be cut into blocks and 
dried in the air) approximately 880 B.T.U. are required. After air- 
drying the intermediate 50 per cent, material, a final product results, 
containing about 20 per cent, of moisture and possessing a calorific 
power of about 8100 B.T.U. per pound. As one pound of the 
original mud yields rather less than one-eight pound of dried peat, 
yielding not more than 1000 B.T.U., it is evident at once that the 
problem cannot be solved by a direct dehydration process such as 
the one outlined above. But it might be possible in such a duplex 
process to substitute electro-osmose for the preliminary evaporation 
and so either to remove mechanically a large part of the water or 
else to concentrate the suspended particles in the pulp by causing 
them to migrate by cataphoresis to the electrodes. It is well to bear 
in mind, in this connection, that the electro- osmotic process cannot 
possibly dry"^ anything ; it can at best remove water only to the 
extent that filter presses or centrifuges do. 

Count Schwerin was granted his first British Patent^ in 1900. 
Various types of apparatus were disclosed, in all of which the peat 
was treated between a suitable anode and a perforated cathode. On 
passing a direct current between the electrodes, water was forced 
out of the spongy or semi-liquid mass and escaped through the 
perforations in the cathode. At the same time some of the sus- 
pended peat migrated to the anode and formed there a fairly dense 
layer. Schwerin called this the " motorial " action of the electric 
current. 

He next patented an apparatus* consisting of a series of superposed 
horizontal partitions, corrugated to allow liquids to flow away, and 
supporting boxes containing raw peat. These boxes were filled with 

2 Cf. Nernst and Brill : Verh. Beutsch. phys. Ges., 11, 112 (1909). 

3 Brit. Pat. 12431 (1900). 
* Brit. Pat., 22301 (1901). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 41 

pervious metallic bottoms serving as cathodes and the anodes pressed 
down from above ixpon the peat. The Hochst Color Works 
exiJerimented with Schwerin's process on a semi-commercial scale 
and took out several additional patents^ on improvements of 
apparatus and procedure. Other patents were taken out in Great 
Britain by Siemens and Halske," DouU/ Kittler,"* Verey and Downes'-* 
and Simm/" although the last named inventor really used the current 
for heating purposes only.^^ 

Schwerin,!- addressing the Bunsen Society at the Fifth Inter- 
national Congress at Berlin in 1903, ditcussed some of the pre- 
liminary experiments made with his process and attracted at the 
time a good deal of attention. Starting with a peat mud containing 
originally nearly 90 per cent, moisture, it was claimed that a volume 
of water equal to three-fourths the volume of the mud could be 
removed and that this could be done with an expenditure of only 
one-fifth part of the energy available in the recovered peat. The 
most suitable potential gradient through the peat was stated to be 
4 or 5 volts per ceniiiiieire and 13 to 15 kilowatt-hours were required 
in removing one cubic metre of water. Unfortunately, the peat 
obtained at the end of the treatment contained as high as 65 per 
cent, of moisture, although the material itself was easily amenable 
to moulding into bricks or other shapes. It was therefore necessary 
to subject the moulded peat to prolonged and tedious drying in the 
air, in order to reduce the water content to the permissible aiaximum 
of 20 per cent. 

Promising as Schwerin made his process appear, it proved a 
failure when tried out on a commercial scale apparently because air- 
drying the material with 65 per cent, moisture proved to be far more 
tedious and costly than experience with 50 per cent, material had 
led those interested to expect.^'^ Nevertheless, it is possible that the 
method may some day prove feasible if the electro-osmotic treatment 
can be improved to yield a product with less than 50 per cent, of 
moisture ; such an improvement might be brought about, as Foerster 
suggests, by previously disintegrating" the jelly-like aggregates in 
the original peat and thus permitting closer packing of the peat 
solids. A very large proportion, however, of the water in peat is 
adsofbed, and the difficulty as I see it lies in the removal of this 
adsorbed moisture ; only water held mechanically can be removed 
by electro-kinetic processes.^* 

In recent years Schwerin has endeavoured to improve things by 
applying to his purposes some of the newer knowledge gained from 

^ Brit. Pats., 3793, 24670 (1901) Farbwerke, vorm. Meister Lucius u. Briining. 

6 Brit. Pat., 14195 (1903). 

' Brit. Pat., 1717 (1903). 

* Brit. Pat., 126 (1904). 

9 Brit. Pat., 2226 (1907). 

'» Brit. Pat., 4792 (1905). 

" Cf. Davis: Bull. U.S. Bur. of Mine.s, 16, 122 (1912). 

" Ber. V. int. Kong, angew. Chein., 4, <J53 (1903) ; /.eit. EleMrochemie, 9, 739 
(1903). 

'3 f. Foerster : EleUruchemie, 118 (1915). 

•^ Cf. Brit. Pats. 6993, 6995 (1914). 

'5 The same difficulty arises in the removal by cataphoresis of iron oxide from 
clay. Cf. the "osmose" process of clay ijurificatiou. 



42 REPORTS ON THE STATE OF SCIENCE. 1918. 

the researches of Perrin and others. By adding a trace of caustic 
alkali to the peat mud, the dewatering is greatly hastened.^^ He has 
also devised an interesting electro-osmotic filter press^'' in which peat 
or clay are dewatered under pressure between filter diaphragms and 
an electric current sent through. It is claimed that by continuous 
pressure and electrical endosmose, the pressure necessary to filter 
clay or peat suspensions may be reduced twenty fold. Further 
improvement is said to be gained by disintegrating^^ in a ball mill 
the peat as it comes from the bog and adding the electrolyte to the 
mill. 

The "Osmose" Process of Purifying and Dewatering Clay. 

The electro-osmose process was next applied to the dewatering 
and purification of .clay,^^ for the purpose of transforming a low 
grade and impure material into something approximately in quality 
ball-clay or china-clay. In the older processes the impure clay is 
first made into a thin slip .with water, the slip is allowed to stand 
until the coarser particles (usually silica) have had time lo settle, 
and the fine particles of clay still remaining suspended in the slip 
are removed by gravity settling, filtration or centrifugal separation. 
The settling procass is very tedious, and the difficulties of filtering 
or centrifuging are very great. 

Schwferin proposed to hasten and improve the process by de- 
watering the suspended clay by means of cataphoresis. The crude 
clay substance is made into a slip with water in the usual way, the 
kaolin is deflocculated (peptized) by the addition of a little sodium 
hydroxide or other agent such as humus or sodium silicate, and the 
coarser particles are allowed to settle. If the impurities such as 
silica or iron oxide happen to consist of relatively coarse particles 
unadsorbed by the clay itself or even if they are finely divided but 
are not deflocculated (peptized) by the addition agents, the crude 
clay is pvirified to a certain extent and is usually improved in 
plasticity and firing qualities. The clay suspension, after settling, is 
pumped into the "osmose" machine where it is dewatered by 
cataphoresis. 

According to Ormandy^^the "osmose" machine consists of a semi- 
circular trough, in the center of which a revolving metal drum 
serves as anode and outside of this drum and distant about half an 
inch from it is a cathode of wire netting, surrounding the anode 
drum on the under side. When the suspension is pumped between 
the electrodes, the impurities are said to settle on or under the wire 
cathode, whence they are removed, while clay is deposited on the 
slowly revolving drum in a blanket 4^ feet wide and ^ inch thick, 
containing not more than 20 per cent, of moisture. For other details 

16 Of. Brit. Pats. 3364, 11626 (1911). 

" Cf. Brit. Pats. 14369, 23545, 24666 (1912) ; 10873 (1913) ; Ulzer : Zeit. aiujew. 
Chem., 28 (1), 308 (1915). 

>8 Brit. Pats. 6993, 6995 (1914). 

IS Cf. Brit. Pats. 10024 (1907) ; 28185 (1911) and others. 

2" Brit. Ciayworker, 22, 9 (1913) ; Pott. Oaz., 38, 1162 (1913) ; 40, 178 (1915). 
Cf. Stoermer : Tonindustrie Zeit., 36, 178 (1915) ; also Hopkins : Brit. Claywurher, 
22, 62 (1913), Cf. Brit. Pats. 725 (1912) ; 3434 (1913), etc. 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 43 

as to operation, size of plant, costs and other matters, Ormandy's 
article and the interesting discussion on the part of members of the 
Ceramic Society should be consulted. 

Among the advantages claimed for the method are (1) greater easf 
and steadiness of operation ; (2) smaller plant-space ; (3) lowei 
labour cost ; (4) process not only dewaters clay but purifies it aa 
well, thus supplementing the preliminary settling treatment, (5) clay 
after treatment is very plastic 'and sinters at a temperature far below 
the melting point.^i 

Schwerin's " osmose " method has been discussed critically by 
Bleininger^^ who points out that the " osmose " machine is merely 
a substitute for the filter press or centrifuge, having the advantage 
over most filter apparatus of being automatic and continuous. By 
experiments of his own Bleininger assured himself that no measur- 
able purification occurred during the cataphoretic separation of the 
clay ani that such change as the clay finally underwent was du« to 
the preliminary deflocculation and settling. At the present time 
Bleininger^* is of the opinion that, although the " osmose " process 
can be made to work satisfactorily, the same results can be obtained 
without the use of the electric current by deflocculating the clay 
with caustic soda, thus removing the granular impurities, coagulating 
the suspension with acids or aluminum chloride and filtering out 
the precipitated material. At any rate no electro-osmose plants are 
in operation in the United States, while the precipitation process is 
giving satisfaction at the Saylersburg, Pa. plant of the Miner-Edgar 
Company, Brooklyn, N.Y., and that of the Georgia Kaolin Co,, at 
Macon, Georgia. 

There seems to be a great deal of misunderstanding with regard 
to the extent to which the "osmose" machine acts as a purifier. 
Ormandy points out that clay or kaolin particles are electro-negative, 
silica is more or less neutral while oxides of iron and titanium are 
positive. Hence only kaolin migrates to the anode, silica settles out 
and the iron collects at the cathode. In the first place, suspended 
ferric oxide, although called a positive colloid, is not necessarily 
positive against an alkaline solution and probably is electro- 
negative^* unless there happens to be present in the solution some 
strongly adsorbed cation, such as calcium or magnesium, to counter- 
act the effects of hydroxyl. Another point which has been over- 
looked is the condition of the iron oxide in the clay — if the oxide is 
adsorbed by the kaolin the electrical treatment cannot remove an 
appreciable amount of iron from the clay. To be sure, Schwerin^s 
claims that adsorption compounds can be broken up by electrical 
endosmose or catapboresis, but this can occur only when there is a 
relativt-ly large amount of one substance in the liquid phase and in 
adsorption equilibrium ivith the solid phase. As to the results 
actually obtained, it is interesting to note that of 25 clays reported 

21 Cf. Brit. Pat. 3434 (1913). 

2-' Trans. Am. Cer. Soc. 15, 338 (1913) ; Tcnhn. Paper U.S. Bur. Standardg 51, 
(1915). 

25 Private communication to the author, June, 1918. 

*< Ferric oxide peptized by glycerine and NaOH is negative and migrates to the 
.•node. Fischer and Kusnitzky : -e;or/tc;« Zei/., 27, 311 (1910). 

2s Brit. Pats. 14369 (1912). 



44 REPORTS ON THE STATE OF SCIENCE. 1918. 

by Ormandy, 15 contained less iron after purification while 8 con- 
tained more. 

Shortly before the w?r, Schwerin organized the Elektro-oemose 
Aktien Gesellschaft of Frankfort-on-the-Main, for the purpose of 
developing his multiplicity of inventions, commencing operations 
•with a capital of three million marks.^^ Several improvements and 
changes have been made in the clay process since that time, along 
the lines of adding negative colloids (silica, humxis) to the clay 
suspension,-'' employing electro-osmotic pressure filterSj^** using 
diaphragms^^ differing (1) in size of pores, (2) in sign and intensity 
of interface potential, and making several changes in the " osmose " 
machine itself. There is not enough available information for one 
at the present time to evaluate those modifications. The process as a 
whole appears to be far the most promising one Schwerin has 
developed. 

Electrical Tanning. 

Electrical tanning^" of leather is the oldest practical application of 
electrical endosmose, having been originated, according to Buse, by 
Grosse in 1849. In 1874 de Meritens at Petrograd used electricity in 
600 tan pits, employing a layer of carbon at the bottom as anode, 
placing on this alternate layers of hides and tan bark and concluding 
with a sheet of zinc as cathode. Buse decribes other systems ( Groth, 
Worms and Bale, etc.) and reports that the electric current increased 
the rate at which tannin was taken up from 338 to 533. 

So far as one is able to judge, electricity has been applied to 
tanning processes for two purposes (1) to hasten the process by 
heating the bath electrically, (2) to hasten the process electro- 
osmotically bj' the tan liquor into and through the skins. For the 
first purpose either direct or alternating current may be used, but for 
the latter only direct current can be employed. It seems incorrect 
to advocate as Williams does the use of an alternating current to 
produce the endosmotic effect of a direct current without at the same 
time causing electrolytic decomposition of the tannins. 

The electro-osmotic method of tanning is decidedly more rapid 
than the ordinary diffusion process and would be a distinct success 
were it not for anodic oxidation of the tannin. Schwerin^^ has 
endeavoured to prevent this by surrounding the electrodes with dia- 
phragms but his- process and apparatus appear to be excessively 
intricate. It ought, however, to be possible to solve all these 
diflBculties, for it is undoubtedly in this field and in impregnation in 
general that electrical endosmose should find widest and most 
successful application. 

26 Eleldrotechn. Zert„ 35. 860 (1914). 

" Brit. Pats. 27931 (1911), etc. 

's Brit. Pats. 23.545 (1912). 

29 Brit. Pats. 2466 (1912). 

=*" Poising : Zeit. Elelitroche.mie, 2, 167 (1893); Rideal and Trotter: Jour. Soc. 
Chem. Tnd., IQ, 42.5 (1891) ; Buse : Ibid., 19, 57 (1900) ; Rideal and Evans : Ihid.. 
32, 633 (1913); Williams: Jour. Am. Leather. Chemists. Assoc, 8, 328 (1913); 
Groth : Brit. Pat. 19239 (1912). 

31 Brit. Pat. 21190 (1914). 



ON COLI-OIJ) CHEMISTRY AND ITS INDUSTKIA I, Al'i'LICATIONS. 45 

Preservation of Timber. Electro-osmotic Impregnation. 

At various times it has been proposed to dry timber by electro- 
osmotically removing the sap. While electrical endosmose can 
scarcely prove suitable for this process alone, it might be very 
eflEective in replacing the sap juices with liquid disinfectants. 
Alcock and Company, Proprietary, Ltd.,^^* of Melbourne, propose to 
impregnate timbers electrically, by placing them on end in a shallow 
cathode vessel containing a conducting liquid and driving into the 
upper ends hollow metal anodes filled with the liquid preserving 
medium with which the wood is to be impregnated. On passing a 
current, electrical endosmose to the cathode takes place, sap is forced 
out of the timber and into the lower receptacle and its place is taken 
by the liquid preservative forced in at the top. If the consumption 
of electric power is not too great, the method ought to prove a 
success. In this connection it is interesting to find a note^^ to the 
effect that the injury to trees caused by stray currents may be due to 
electrical endosmose. This is quite possibly true in case the electric 
current is a direct one. 

Manufacture of Bricks. Lubricating Metal Surfaces in Contact 

with Clay. 

A very effective and apparently mysterious process which is 
unquestionably an application of electrical endosmose was announced 
by Dawkins^^ in 1913 at the Chicago Convention of the National 
Brick Manufactures Association. Wet clay has a distinct tendency 
to adhere to smooth metal surfaces. To prevent this a lubricant is 
used, the lubricants including oils, emulsions and water itself. 
Water is particulai'ly useful because a layer of it on the meta) 
prevents the clay from sticking, softens the surface of the clay as it is 
being cut or moulded and gives the brick a smooth finish. It was 
found that if metal in contact with the clay is made cathode and a 
current is passed, the clay no longer tends to adhere and all the 
effects of lubrication are duplicated. In making wire cut bricks 
electrical •' lubrication " is said to reduce the power consumption by 
25 to 30 per cent. 

It has been suggested that the current forms a layer of hydrogen 
over the electrode and that this causes the apparent lubrication. 
What really happens is this : when the current flows water is carried 
through the clay to the cathode (the metal) and forms a layer 
between it and the clay ; it is this layer of water which prevents the 
clay from sticking and acts as a lubricant. 

Electro-therapeutics. Electro-osmotic Infiltration of 

Drugs.^* 

Shortly after the early experiments, especially those of Wiede- 
mann, had demonstrated the ease with which electrical endosmose 

"« Brit. Pat. 2517.5 (1910). 

32 Schneckenberg : Elektrochnm. Xeit., 19, 131 : Chem. Abstr. 

« Clayworker 57, 426 (1912) Cf. Brit. Clayworker : 22. 91, 92 (1913). 

'< Morton : Cataphorenu (1898) ; Herdman : Bigelow's Interiwt. Sys. of Thera- 
peutics, 30, (1894) ; Peterson : Ibid. 1 (1894) ; Jones : JJed. Electricity (4th Ed.) 
330 (1904) ; Traube and Berczeller : Internat. Zeit. Biol. 2, 107 (1915). 



46 REPORTS ON THE STATE OF SCIENCE. 1918. 

occurs through animal membranes, attempts were made to apply the 
process to living membranes and tissues. In 1859 Richardson pro- 
duced what he termed " voltaic narcotism '" or local anaesthesia pro- 
duced electrically by forcing morphine through the skin and into 
the tissues of the subject. The process appears to have been a com- 
bination of electrolysis and electrical endosmose. Since Richardson's 
time a great deal of interesting work has been done on the subject 
and it has been quite conclusively demonstrated^^ that liquids bearing 
narcotics or drugs of all kinds can be forced by the electric current 
into and through living skin and tissue. Electrical endosmose has 
been applied in dentistry as well, in the local anassthesia^*^ of sensitive 
dentine and in bleaching teeth with hydrogen peroxide.^'' Electric 
transference of ions in solution complicates most of these so-called 
" cataphoretic " experiments (such as Edison's^® on the infiltration of 
lithium chloride) as Leduc has shown.^^ 

Miscellaneous. 

Schwerin has patented an electro-osmotic process*" of extracting 
sugar from beet. Sliced beet roots were placed between pervious 
walls and electrolyzed. The siTgar solution containing the soluble 
albumenoids was driven through the cathode diaphragm and in this 
manner the beets were extracted. By placing water between the 
anode and the anode diaphragm the soluble acids in the beets were 
said to be removed by electrolysis and collected — an improvement 
which prevented the sugar from inverting. The process appears to 
have been electrically accelerated dialysis, except in so far as the 
acidic impurities were more or less segregated. In more recent 
years Schwerin through the Elektro-osmose A.G. has been granted 
a large number of patents dealing with the purification of colloidal 
and non-colloidal mixtures and the resolving of such mixtures into 
their constituents. By using diaphragms impervious to the colloid 
but pervious to dissolved ions, the latter may be driven out by 
electrolysis and collected about the electrodes which are usually 
surrounded in the beginning by pure water. A simple example is 
the case of extracting sugar and acids from beets, which we have 
just mentioned. Suspended colloids may themselves be fractionated 
by using diaphragms (1) the pores of which vary in size (Cf. ultra- 
fitration) (2) the interface potentials of which are difi'erent. When 
the diaphragm, operates because of differences in permeability (size 
of pores) one is dealing with ultrafiltration accelerated by electrical 
endosmose. In the other case negative diaphragms are said to hold . 
back positive colloids or vice versa and here the process is analogous 
to the mutual precipitation of electrical suspensions. It is doubtful, 
however, whether really satisfactory separations can be made by this 

35 Cf. Barratt and Harris : Biochem. Jour., Q, 315 (1912) ; Morton : Cataphoresis 
89 (189S). 

56 Morgenstern : Electrodiem. Zeit., 15, 189, 214, 240 ; Cf. Chem. Abdr. 3, 1203 
(1909). 

" Morton : Cataphnreds, 41 (1898). 

35 Peterson : Bif/ploiv\'< Internat. Si/g. of Therapeutic? C13 (1894). 

39 Jones : Med. ElectricUy (4th Ed.) 22S (1904). 

« Brit. Pat. 8068 (1901) ; 14195 (1903). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 47 

second method because the adsorption of the suspended colloid may 
change the sign of the diaphragm. Schwerin claims to apply the 
method in the production of pure colloidal silica,''^ in the tanning of 
leather, in the purification of gelatine (glue)''- dyes,'^ metal sols" and 
alumina*^ and in the treatment of serum. 

Summary. 

In this report there have been described applications of electrical 
endosmose or of electrical endosmose and cataphoresis in the pro- 
cesses of dewatering peat and other substances ; treatment of clay ; 
tanning ; filtration ; medicine ; separation of colloidal and non- 
colloidal mixtures ; and so forth. No mention has been made of 
certain processes, such as the electrical treatment of emulsions and 
the use of addition agents in electro-plating, which are clearly in- 
stances of applied cataphoresis and are so recognized. 

British Patents. Electro-osmotic Processes. 

In the case of Patents dated as of the years 1900 to 1013 inclusive 
the original Specifications have been consulted. The information 
contained in the more recent patents has been obtained from 
Chemical Abstracts and other sources. 

1900. 

12481, July 10. B. Schwerin, Munich. " Improvements relating 
to the extraction of ivater or other liquid from mineral, 
vegetable and animal substances.'''' Evidently fiz'st British 
patent. Discusses electrical endosmose, the utilization of the 
" motorial " action of the electric current in removing water 
from peat and describes apparatus for so doing. 

1901. 

8086, April 19. B. Schiverin, Munich. " Improvements relating 
to the extraction of sugar. Sliced beet-roots placed between 
pervious walls and submitted to electro-osmose and elec- 
trolysis. Sugar, soluble albumin and water driven to 
cathode. Places water between solid material and anode ; 
the acids in the beets collect by electrolysis in the anode 
liquid and are prevented from inverting sugar. Describes 
apparatus. 

S2301, November 5. B. Schwerin, Berlin. Cf. 12431 (1900). 
Describes apparatus for dewatering peat. 

1903. 
1717, Jan. 23. J. DoulJ. Use of electric current in drying 

materials. 
14195, June 25. C. D. Abel for Siemens and Halske A. G., 

Berlin. Elaborate discussion of electrical endosmose and 

" Brit. Pat. 9237 (19U). 

•'3 Brit. Pats. 21448, 21483 (1914). 

" Brit. Pats. 95fi5, 9566 (1916). 

<JBrit. Pat. 9261 (1914). 

<i Brit. Pats. 6727, 7212(191,5). 



48 REPORTS OJS THE STATE OP SCIENCE. 1918. 

cataphoresJs. Use of diaphragm aids in removing water from 
peat. Interesting to note that water passes to anode when 
current is passed through a porous cup containing iron 
" oxychloride " (colloidal ferric hydroxide) and the " oxy- 
chloride " is reduced to a jelly (dewatering of colloidal 
suspension with subsequent formation of an iron oxide 
jelly). Purification of " saccharine juices." 

1904. 

126, Jan. 4. B. Kittler, Memel, Germany. Apparatus (con- 
tinuous) for dewatering peat. 

8795, Feb. 16. Tmray for Farhwerke, vorni. Meister, Lucius u. 
Briining Hochst, ajM. Dewatering peat. Heats apparatus 
and material. Cf. 12431 (1900). 

24670, Nov. 14. Imray for Farhwerke, vorm. Meister, Lucius 
u. Briining Hochst, ajM. Dewatering peat. Ingenious 
apparatus for continuous operation, consisting of two endless 
belt conveyers, one of which may be an electrode. 

1905. 

4792, March 8. W. Simm. Dewatering peat. Doubtful if 
Simm really uses electrical endosmose at all as he specifies 
alternating current. Mentions heating effect of the current. 

1907. 

2226, Jan. 29. J. C. Verey and L. Doivnes. Electric-osmotic 
apparatus for dewatering peat. 

10024, Apl. 30. Farhwerke, vorm. Meister, Lucius u. Briini^ig, 
Hochst alM. Depositing suspended particles on electrodes 
by cataphoresis. Fractional cataphoresis, with especial 
emphasis on purifying and dewatering clay. Better results 
are obtained by causing fresh suspension to enter cell by 
passing close to a cathode of large surface. In this way the 
suspension passes through a diluted region and settling out 
of impurities is facilitated. 

1909. 

10793, May 6. B. Schwerin. Production of electric current by 
Quincke's method (diaphragm currents). Claim is made of 
the use of suitable electrolytes to increase effectiveness of 
process. Importance of making certain that diaphragm and 
liquid are in equilibrium. " Action of electrolytes is so 
great, it seems generation of current is dependent upon 
presence of ions." With diaphragms of quartz, an alkaline 
liquid (pyridine and water), pumped through under pressure 



gave the following results 



Pressure. 


Volts. 


Amperes. 


10 


4 


0-01 


20 


8 


0-02 


40 


16 


0-04 


80 


32 


0-08 



Watts. 
0-04 
0-16 
0-64 
2-56 



The efficiency was calculated from the formula : 

_,^ . • volts X amperes 

Lihciency = y- — \ c r~ 

•' pressure x discharge of water 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 49 

It was found experimentally that the efficiency remained the 
same for each of the above pressures but increased as the 
pores in the diaphragm became finer because the discharge 
of water at constant pressure was thereby lessened. 

1910. 

133, Jan. 3. F. Arledter, Hamburg. Electric sizing of paper 
(cataphoresis ?). 

25175, Oct. 39. A/cock and Co. Proprietary Ltd., Melhoiirne. 
Drying timber by electrical endosmose. Stand timber on 
end in shallow vessel as cathode containing a small quantity 
of conducting liquid and connect top of timber with suitable 
anode. Sap is driven endosmotically out of timber into 
lower vessel, following which solutions of resin, sugar or creo- 
sote may be driven in from above and the timber impregnated 
with preservative. 

1911. 

8364, Feb. 9. B. Schwerm. Accelerates process of electro- 
osmose (cataphoresis) by adding acids (acetic acid, CO2, etc.) 
to those substances which migrate to cathode and bases 
(NaOH, NH4OH) to those substances which migrate to anode. 
Hastens draining of peat by adding a little alkali to the pulp. 
An interesting application of Perrin's rule. In 2379 (1911) 
Schwerin patents use of acids to peptize substances (elutriate) 
which wander to cathode and bases to peptize substances 
which wander to anode. 

11686, May 13. B. Schwerin. Adding electrolytes, especially 
Na2S04 to peat. Data on improvement which results are not 
particularly convincing. 

17597, Aug. 2. Felten and Guilleaume Carlswerk A. G., Carl- 
siverk. Claim use of non-aqueous solvents in electro-osmotic 
(cataphoresis) separations. Separation of dyes in alcohol, etc 

27931, Dec. 12. B. Schiverin. In 3364 (1911) use of electrolytes has 
been claimed. In order to cause deposits at electrodes to 
adhere more firmly to latter add electro-positive or electro- 
negative [adsorbed] colloids. For example, peptizes clay 
with a little sodium silicate, allows coarse particles to settle out 
and electrolyzes. With 100 volts and 1 • 6 amps., obtains 140 g., 
containing 65 per cent, clay, in 5 minutes. Ulay adsorbs 
electro-negative colloidal silicic acid from water glass and is 
carried to the anode. 

28185, Dec. 14. Gesellschaft fiir Elektro-osmose {Schwerin). 
Frankfurt ajM. Dewatering and purifying clay. Defloc- 
culates clay with dilute NaOH, allows thin slip so made to 
settle in vats, and finally treats in "electro-osmose" machine. 
Electrolyte added supposed to peptize clay and coagulate 
impurities. 

1912. 

725, Jan. 9. Gesellschaft fur Electro-osmose. Frankfurt ajM. 
Apparatus (osmose machine) for purifying and dewatering 
clay. Rotating cylinder anode and wire gauze catliode. Cir_ 



60 REPORTS ON THE STATE OF SCIENCE. 1918. 

culating device to prevent impoverishment of suspension 
between anode and cathode. 

10370, May 1. J. E. Jameson and O. H. Valpy, London. Electric 
current passed into peat at 100°C. and under pressure (10 Atm.). 
Current may be "continuous or alternating" (sic), and ''de- 
composes hydrocellulose." It is possible that the alternating 
current in some manner breaks down the jelly of peaty 
material. 

14285, June 18. B. Schwerin. Use of electro-osmose in connec- 
tion with manufacture of refractory articles, baked without 
binder. 

14369, June 19. B. Schwerin. Separates mixtures of different 
substances in suspension by fractional cataphoresis. Also 
separates by means of diaphragms of |different permeability ; 
Apparatus really a kind of electric "ultrafilter." 

19239, Aug. 22. L. A. G7'oth, London. Electric tanning. Details 
of apparatus. 

23545, Oct. 15. Gesellschaftfur Elektro-osmose (Schiverin). Dry- 
ing peat, clay, kaolin, etc. by pressure combined with 
electro-osmose Electro-osmotic filtration. Pressure may be 
reduced from 20 atmospheres to 1 atmosphere by combining 
electro-osmose (cataphoresis) with it. The higher the voltage 
used the more rapid the filtration. Apparatus. 

24666, Oct. 28. B. Schwerin. Use of electrically charged dia- 
phragms in the fractional separation of suspended colloids, 
depending upon 

1. Difference in size of pores 

2. Differences in interface potentials. 
Electro-negative diaphragms tend to hold back electro- 
positive colloids and vice versa. 

29826, Dec. 27. Gesellschaft fiir Elektro-osmose and H. Illig. 
Improved apparatus for dewatering and purifying clay. 
Cf. 725 (1912). 

1913. 

S434, Feb. 10. Gesellschaft fiir Elektro-osmose {Schwerin'). 
Making ceramic articles without adding flux to cause sintering 
at temperatures below melting point. No flux (steatite, 
magnesium silicates) necessary with clay purified by electro- 
osmose, owing to the extreme fineness of tlie particles. In 
one case a clay treated by the osmose process sintered at a 
temperature more than 300° C. below its melting point, and 
did this without the addition of a flux. 

6668, Mar. 18. A.L.C. Nodon, Bordeaux. Electrical preser- 
vation of railway sleepers (ties). Uses alternating current (?) 
and 1 per cent. ZnClo solution. 

10873, May 8. Gesellschaft fiir Elektro-ostnose (Schwerin). Cf. 
23545 (1912) Electro-osmotic filter with electrodes of hard 
lead. 

26661, July 21. Gesellschaft fiir Elektro-osmose (Schwerin). 
Further mechanical improvements in osmose machine for 
clay. 



jdH 



O^V COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 51 

1914. 

6993, Mar. 19. Elektro-osmose AM. Qesellschaft (Schwerin). 
Facilitates dewatering of peat by previously subdividing 
material in a ball mill and adding electrolyte such as NaOH 
to increase the rate of cataphoresis and endosmose. 

6995, Mar. 19. Elektro-osinose AM. Gesellschaft (Schiverin). 
Gf. 6993 (1914). Adds adsorbed colloid before grinding 
peat. Colloidal silicic acid or humic acids are suitable. By 
adding sodium silicate obtains both a suitable electrolyte 
(NaOH) and colloidal silica. Adsorbed colloid peptizes the 
solid and being strongly electro-negative in dilute NaOH 
hastens the migration to the anode. 

92S7, Apr. 14. Gesellschaft fur EleMro-osmose {Schiverin). 
Electro-osmotic preparation and purification of colloidal 
silicic acid. Places 5 to 10 per cent, sodium silicate solution 
between two porous diaphragms — one around cathode and 
the other around anode. By using a neutral diaphragm 
(composed of carborundum plus alundum) about the cathode, 
the alkali is electrolyzed out of the sodium silicate, and no 
silica is carried into the cathode compartment, since no 
electrical endosmose takes place through the cathode dia- 
phragm. With parchment above anode, no colloidal silica can 
get into anode compartment but soluble acids can do so. 
Obtained colloidal solution of silica in the middle compart- 
ment. Platinum or lead-antimony ^anodes ; brass gauze 
cathodes. Typical " electro-osmotic " multiple diaphragm 
process. Of. German Pat. 283,886, Apr. 15, 1913. 

9261, Ai^r. 14. Qesellschaft fur EleMro-osmose {Schiverin). 
Making stable metal Sols by using colloidal silicic acid as 
protecting agent, reducing metal salt with hydrazine hydrate 
and purifying sub(?equently by process such as specified in 
9237. 

11828, May 13. Gesellschaft fiir EleMro-osmose {Schiverin). 
Separating colloids, etc. by electrical endosmose and cata- 
phoresis. 

19849, Sept. 16. Gesellschaft fiir EleMro-osm.ose {Schwerin). 
Tanning and dyeing by electro-osmose. Places leather or 
adsorbing substance together with tannin solution in com- 
partment bet-sreen two or more diaphragms, impervious to 
tannin but pervious to dissolved electrolytes. Claims simul- 
taneous purification of tannin solution by electrolysis and 
impregnation of leather. 

21189, Oct. 19. Gesellschaft fiir EleMro-osmme {Schiverin). 
Changes interface potential of diaphragms by addition agents. 
Thus Cr203, makes a leather diaphragm more positive (leather 
adsorbs Cr203 which is distinctly electro-positive). Methylene 
blue (basic dye) makes viscose positive (viscose adsorbs the 
dye cation). Adsorbed acid dyes make diaphragms electro- 
negative. Interesting patent based on selective ion adsorption 
or on the adsorption of charged colloids. 

21190, Oct. 19. Gesellschaft fiir EleMro-osmose I {Schiverin). 
Modifies 19849 to allow preliminary purification of tan liquor. 



52 REPORTS ON THE STATE OF SCIENCE. 1918. 

Uses three diaphragms instead of two and places tan liquor 
next the' hides in a separate compartment between the hides 
and the cathode. Anode, cathode and hides are immersed in 
water. On passing current acid and basic impurities in the 
tan liquor are electrolyzed out and carried into the anode and 
cathode compartments, after which tannin is said to migrate 
into compartment containing hides. Process seems hopelessly 
complicated and not at all practical. Theory of process not 
very clear. 

21448, Oct. 23. B. Echwerin. Gelatin or glue placed between 
diaphragms impervious to glutin and electrolyzed a cell con- 
taining anode, cathode and gelatin compartments. Soluble 
electrolytes removed and albumins precipitated. Other com- 
plicated modifications are described. Combined electrical 
dialysis and uHrafiltration process. 

21483, Oct. 24, Gesellschaft fur Elektro-osmose (Schwerin). 
Of. 21448 (1914). Uses hide or leather waste between 
diaphragms instead of glue. 

1915-1916. 

6727, May 5. Elektro-osmose, Akt. Gesellschaft (Schwerin). 

Electrical purification of alumins. Cf. 21448 (1914). 
7212, May 13. Elektro-osmose Akt. Gesellschaft (Schwerin). 

Cf. 6727. Electrical purification of alumina. 
7590, May 20. Elektro-osmose Akt. Gesellschaft {Schwerin). 

Use of centrifuge to hasten preliminary settling process in the 

" electro-osmotic " purification of clay. 
9565, 9566, June 80. Elektro-osmose, Akt. Gesellschaft {Schwerin). 

Electrical purification of dyes. Dye suspension placed in inner 

compartment and shielded from oxidizing and reducing action 

of electrodes, by means of diaphragms impervious to dyes. 

Cf. 2144S (1914). 
11659, Aug. 12. Elektro-osmose, Akt. Gesellschaft {Schwerin). 

Treatment of clay. 

COLLOID-CHEMISTRY IN THE TEXTILE INDUSTRIES : 

W. Harrison, M.Sc, Lecturer in Textile Chemistry, 
The University, Leeds. 

Introduction. 

Although a considerable amount of research work has been done 
on the chemistry of textile fibres, particularly cotton, no definite 
information has been obtained on the chemical constitution of the 
substances composing them. The colloidal nature of these sub- 
stances always stands in the way of pure chemical research. There 
are many processes used in the textile industry where a knowledge 
of the chemical constitution of the substances composing fibres is 
unnecessary, the changes produced being more physical than 
chemical. Chemists are naturally attracted by the idea that all the 
physical properties of a substance are dependent on the chemical 
constitution of its molecules, but the properties of colloidal barium 



1 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 53 

sulphate are quite different from those of the crystalline substance 
although the chemical constitution is considered to be the same in 
the two cases. The suggestion has been made^ that colloidal barium 
sulphate consists of extremely minute crystals, but this does not 
explain the difference in physical state. The chemist's idea can only 
be upheld by a considerable modification in the conception of 
molecules as present in solid substances. The Braggs^ have estab- 
lished beyond doiibt that the fundamental units of a crystal are 
atoms, not molecules. Many chemists^ — ** have cast doubt on the 
crystal models of the Braggs', except that of the diamond, simply 
because they are against the generally accepted ideas on valency. 
It has been suggested^ that one of the interesting problems of the 
future will be to reconcile the X-ray crystal models with the 
molecular hypothesis. Since the X-ray models have been deduced 
from positive evidence whereas no positive evidence has ever 
obtained in favour of the molecular hypothesis as applied to solids, 
the author considers that it is the molecular hypothesis which 
requires broadening. The original definition of a molecule was the 
smallest particle of a substance which could exist ; with the dis- 
covery of chemical polymerisation this definition has been narrowed 
somewhat. The author considers that the difficulty of reconciling 
the X-ray models with the molecular hypothesis disappears if one 
admits a crystal to be a polymeride or single molecule as suggested 
by Langmuir.i^ This idea has far-reaching consequences of very 
great importance in colloid chemistry, since the necessity for 
admitting a high molecular weight as a special characteristic of 
colloids disappears. A single crystal may be considered as a single 
molecule since it consists of atoms bound together by the same 
forces which bind together the atoms in the simple molecules found 
in gases. The molecular weight of the crystal is then proportional 
to its size. This view is entirely in agreement with the observa- 
tions in brownian movement of particles in different degrees of 
dispersion which were shown by Perrin^'^ to be explained by the 
kinetic theory of gases. There are numerous other consequences of 
the idea of considering crystals as polymerides which it is not 
intended to discuss here. 

Regarding the chemical nature of fibres, chemists have divided 
opinions, some considering them to be very complex bodies of high 
molecular weight, others to be physical forms of insoluble substances 
of possibly low molecular weight. These opinions may be taken to 
be identical in the light of the idea discussed above. 

In the case of vegetable fibres, the suggestion has recently been 
made" that the fibre substances, celluloses, are liquid systems ; this 
brings forward the question of reconsidering the definitions of 
liquid and solids. At present, these are somewhat rigid and bodies 
possessing properties of both states of matter are considered to be 
mixtures. The author does not hold this view, but considers that 
there is no distinct line of demarcation between the solid and liquid 
states any more than there is between colloidal — and true — solution. 
The semi-solid state of many colloids does not necessarily imply the 
presence of both solid and liquid phases. It is, therefore, still an 
open question whether the celluloses are mono — or diphasic systems. 



54 REPORTS ON THE STATE OF SCIENCE. — 1918. 

The fibres possess many physical properties in common with 
other colloids such as indiarubber and gelatine. 

When subjected to stress in a dry condition they become deformed 
and acquire increased double refraction which persists when the 
stress is removed. ^^ This increased double refraction shows the 
presence of extra internal stresses resultina: from the deformation. 
When placed in a solvent which tends to produce swelling — water 
in the case of fibres — these extra internal stresses disappear and the 
fibres regain their original shape. When compressed under boiling 
water most fibres become permanently deformed, no internal stresses 
being produced. 

These theoretical points have an important bearing on many of 
the phenomena met with in the treatment of textile materials. 

(A) Introduction. 

1 Von Weimarn, Grvwlzitge der Dispe.rso^d cheviic, Leipzig (1912). 

» W. H. Bragg and W. L.'Brasrg, Proc. Boy. Soc. A. 87) 277 (1914), etc. See also 
Tram. Chem. Soc, p. 252 (1916). 

3 A. Smits and F. E. C. Scheffer, Proc. K. Aliad Wetlemch, Amsterdam, 19, 432 
(1916). 

* A. Fock, Centr. Min. 392 (1916). 

^ J. Beckenkamp, ihid. 97 (1917). 

6 J. Stark, Jahr. PadioaMiv. EI.ectoniJt, 12, 280 (1915). 

? F Rinne, ^eit anorg. Chem., 96, 317 (1916). 

8 P. Pfeiffer, ihid., 92, 376 (1915) ; 97, 161 (1916). 

' H. M. Dawson, Animal Peport Chem. Soc. {Physical Chemistry') (1917). 
'" J. Perrin, Broiviiian Movement and Molecular Peality. 

*i C. F. Cross, Presidential Address to Soc. Dyers and, Colourists, 34, 19 (1918). 
12 W. Harrison, Proc. Boy. Soc. A. 94, 460 (1918). 

" I. Langmuir, Joi/rn. Amer. Chem. Soc, 28; 2221 (1916). 

'■i Tinker, Proc. Boy. Soc. A 92, 357 (1916). 

>5 W. Moeller, KolL Zeit. 19, 205, 213 (1916) ; 20, 242, 257 (1917) ; 23, H (1918). 

18 J. E. Katz, Koll. Ch. Beith., 9, 1 (1917). 

17 Bachmann. Koll. Zeit, 9, 312 (1911) ; H, 1.50 (1912) ; 12. 204 (1913) ; 23, 8.5, 
(1918) ; also Zeit. ariovg. Chem., 73, 125-172 (1911) ; 79, 202 (1912) ; IQO, 76 (1917). 

18 Debye& Scherrer, Phys. Zeit., 18, 291 (1917). 

Cotton. 

Regarding the chemical constitution of the substance of the 
cotton fibre, six foi'mulae have already been prf^posed, but none of 
these have been established. (Refs. I'J-i^'^^ 

Cross originally held that the cellulose molecule was large, being 
composed of units of a certain type bound together ; Green favoured 
a simple formula. In a recent address (Ref. A.") Cross stated that 
there are no grounds for the assumption of large molecules in the 
strict chemical sense. He considers that the celluloses are liquid 
systems capable of large volume changes and also solution -aggregates 
of amphoteric character. He suggests that the units in the cellulose 
aggregate may have dimensions less than C,,. One difficulty in the 
way of the acceptance of a very simple formula for cellulose is tlje 
number of hydroxyl groups which chemical methods prove to be 
present ; all the bodies of the same chemical composition, known up 
to the dimension C7, having a corresponding number of h^'droxyl 
groups are soluble in water. 

It is quite likely that the units in the cellulose aggregate are 
bound together in a similar manntr to the units in a crystal, although 



ON COLLOID CHEMISTRY AXD ITS INDUSTRIAL APPLICATIONS. 55 

perhaps not in a regular formation. As already suggested, there is no 
necessity to discuss the molecular weight of the cellulose colloid 
since it only exists in the solid state. The fibre itself may be con- 
sidered to be a molecule iu so far as the atoms composing it are 
bound together in the same way as in any other molecule. 

Mechanical disintegration produces changes corresponding to 
depolj'merisation, B ^^- -'' ^^- ^*- ^^ in the same way that mastication is 
considered to produce depolymerisation of rubber. (Compare 
Journ. Soc. Chem. Incl, 37, 313a (J918).) 

The substance of the cotton fibre is known in many colloidal 
states ; in the fibre itself it exists as a porous, adherent mass, showing 
turbidity in the ultramicroscope, which indicates amicroscopic 
structure. Treatment with sulphuric acid of 1'70 Sp G causes the 
fibre to swell and eventually pass into solution. In the swollen 
state the fibre shows a distinct granular structure, which the author 
succeeded in photographing.^^-^ Since the acid acts in the direction 
of solution and not coagulation, the author is of the opinion that the 
structure of the swollen fibre is an extension of that of the original 
fibre, this extension allowing the structure to be resolved. 

The double refraction of cotton fibres has been shown to be due to 
the presence of internal stresses, which become active when the fibre 
is softened.22-23 There is no doubt that the cellulose is in different 
colloidal states in different parts of the cotton fibre, the outer portions 
being more solid than the inner. There are markings on the fibre 
(Refs. ^~^^) which have physiological importance which it is not 
proposed to discuss in this review. The colloid chemical investiga- 
tion of cotton indicates that it is first formed in somewhat gelatinous 
filaments which harden from the outside by drying or by some 
ch«;mical change. 

The following extract from W. L. Ball's observations on the 
development of cotton appear to be in agreement with the view just 
expressed : — 

" The full diameter of the seed hair is attained almost at once, 
when its length is only yV ni.m. while its length continues to in- 
crease until the 25th day of development after which its wall begins 
to thicken, giving strength to the lint. This thickening is not 
uniform but leaves simple pits in the wall set obliquely, and the 
closure of these pits when the wall dries after the boll opens, gives 
twist to the fibre. The uninucleate cell contents remain alive until 
the boll begins to open, when they die from desiccation." 

" The cell wall is extremely thin for the first three weeks and the 
cuticle which covers it can scarcely be differentiated unless the 
wall has been swollen with Schweitzer's reagent when (being 
unaffected by the ammoniacal copper oxide) it causes the familiar 
beaded appearance, the cellulose of the wall swelling through the 
torn places in the cuticle." 

The difference between the outer cell wall or cuticle and the 
inner portions of the fibre is most probably one of colloidal state-^ 
and not of chemical nature. A similar difference exists between the 
outer layers of starch granules and the inner portions and it has been 
shown that this difference is one of colloidal state. 



66 BEPORTS ON THE STATE OF SCIENCE. — 1918. 

The colloidal state of cellulose is modified in the direction of 
distension by treatment with strong alkalies, caustic soda, caustic 
potash tetramethyl-ammonium-hydroxide and by several other sub- 
stances. A still greater degree of swelling is produced when cotton is 
overworked in the hollander used in the paper-making industry .^^ 2® 
The maximum degree of dispersion is attained when the cotton is 
treated with cellulose solvents. 

It has been observed that freshly precipitated cellulose is soluble 
in caustic soda but that this solubility disappears when the cellulose 
is dried. A similar change is produced when precipitated starch is 
dried. These changes are the common result of gel-dehydraiion. 

Iodine forms a useful reagent in conjunction with hydrating 
agents such as potassium codide, zinc chloride and sulphuric acid, 
for indicating the different colloidal states of cellulose. The strength 
of hydrating agent required to give the blue colour indicates the 
degree of dispersion of the cellulose. It is interesting to note that 
starch celluloses can be prepared which give the blue colour with 
iodine under the same conditions as cellulose.-^ This does not neces- 
sarily imply that there is any chemical relationship between starch 
and cellulose since the blue colour has been shown to be due to 
colloidal iodine and numerous substances have been found which 
give the reaction. 

(B). Cutton: 

Boohs of Referetiee. 

' Cross & Bevan, Cellulose and Researches. 

^ Schwalbe, Die Cellulose. 

^ Worden, JVitrucelliiluse Industry. 

* 0. N. Witt, C/iem. Tech. der Gesinnnst-fasern Braunsckwcig, (1888). 

5 Monie, The Cotton Fibre, London, (1890). 

^ Bowman, The Structxire of the Cotton Fibre. 

' H. Kuhn, Die Bauinivolle. 

« Flatters, The Cotton Plant, (1906). 

^ W. L. Balls, The Development and ProjJerties of Raw Cotton, (1915). 

References. 

'" Tollens, Handbxich der Eohlehydrate II., 252 (1895). 

" Vignon, Bull. Soc. Chem., 21, 599, (1899). 

" Bernadou, (Compare (2), p. 349). 

'5 Cross & Bevan, Trans. Chem. Soc, 79, 366, (1901). 

" A. G. Green, Journ. Soc. Dyers 4' Cols. 20> 117, (1904). 

'^ Cross & Bevan, Ibid. 32, 135, (1916). 

'6 A. E. Sunderland, Ibid. 32, 230, (1916). 

" Crum, Trans. Chem. Soc , 1, 409. 

'8 Muller Jacobs, Journ. Soc. Di/ers Jf- Cols., H, 95, (1885). 

'9 H. De Mosenthal, Journ. Soc.'Chem. Ind., 23, 292, (1904) ; 26, 4*3, (1907). 

-" Haller, Zeit.fiir Farben u. Textil Chem., 8, 125, (1907). 

=' Herzog, Koll Zeit., 5, 246, (1909). 

" W. Harrison, Jorirn. Soc. Dyers Jj" Coh: 31, 198, (1915). 

23 W. Harrison, Trans. Nat. Assoc. Cotton Manfrs., 101, 201. (1916). 

2* Haller (Structure of Cotton), Koll. Zeit.. 20. 1^7, (1917).' 

" Cross, Papier Zeitung, 33, 3246, (1908). 

26 Briggs, Papier Fabrikant, 5, 2644, (1907) ; 46, (1910). 

=' Fenton (Action of hydrochloric acid). Trans. Chem. Soc, 73. 554, ri898") • 7^5 
427, (1899) ; 79, 361, 807, (1901) ; 99, 1193, (1911). ' 

-■8 Erdmann Ac Schaeffer, Ber., 43, 2398, (1910). (Dry distillation of cellulose) 

-'3 Pictet and Sarasin, Comp. Rend., 166, 28, (1918). (Dry distillation of cellulose 
and starch). 

^0 Sarasin, Arch. Sci. phys. Nat. (1918) pp. 5-32. 

3' Fort, Jirurn. Soc Duers 4' Cols. 34, 9, (1918). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS . 57 

•■'2 S. Jucld Lewis, Ihld. 34, 167, (1918). 

" W. L. Balls, Joiirn. Sac. Artf:. p. H89, (1918). 

^* C. F. Cross. Joiim. Sor. Dijeiit c'f- Cols. 34, 215, 247, (1918). 

3* W. Harrisou. IhUJ. 34, 218, (1918). 

36 Knecht & Hall, Ibid. 34, 220, (1918). 

Compound Celluloses : 

3" Cross & Bevan, CelluUmc, pp. 89-232. 

3' Schwalbe, Die Cellulose, pp. 366-483. 

^' Stocks, JJTO^ Report on Colloid Chemistry, pp. 58-64. 

Animal Celluloses: 

<" Worden, Nitrocellulose Industry, p. 1. 

<i Irvine, Trnw.*. C/iem. Soc., 95, 564, (1909). 

Cellulose Solutions. 

The so-called solutions of cellulose are really colloidal solutions. 
The best known solvents are Schweitzer's reagent, ^ ^^ ^i ^j^c chloride 
solution and sulphuric acid. Numerous other solvents have been 
found in recent years. '' Recently, ^ it has been stated that cellulose 
can be dissolved in solutions of most salts when heated under 
pressure. 

Regarding the solution of cellulose in ammoniacal copper solution 
Cramer ^ came to the conclusion from osmotic measurements that it 
was a true solution. Erdmann, i" on the other hand, considered it 
to be a very highly hydrated gel. Ci'oss & Bevan ^'^ expressed the 
view that the copper compound combined with the cellulose to form 
a colloid double salt, i^^^o -pj^g dialysis of these copper solutions has 
been studied by Grumaux ^^ -Rrho came to the conclusion that it was 
the non-d-ialysable portion of the solution of copper hydrate in 
ammonia which acted as a solvent for cellulose. 

It is important to note that cuprammonium hydroxide is not so 
string an alkali as caustic soda. ^^ 

The solution of cellulose in ammoniacal copper solution has been 
stated to be optically active ^^"^^ a view which does not appear to be 
substantiated, i*^ The solution of cellulose in hydrochloric acid is 
optically inactive. ^^ 

(0) Cellulose Solutions. 
' Compare B.' 
^ Compare B.- 
3 Compare B.^ 

■• Czapek, Biochemie dcr Pfhinzcn, Jena, 1905. 
'" Abdcrhalden, Biochem, Ilandlcrilion, Berlin, 1911 (II) Cellulose. 
6 Schweitzer, Journ. fiir priM. Chem. 72, 109. 3441 (1857). 
' Deming, Journ. Anier. Chem. Sue., 33. 1^15 (1911). 
s Weimarn, Koll Zeit, \\, 41 (1912). 
8 Cramer, Journ. f/ir pralif. Chem., 73> 1 (1^58). 
1" Erdmann (Compare B', p. 11). 
" Cross it Bevan, Textbook of Papermaking', p. 8. 
'2 Grumaux, Covq}. Rend., 98, 1885. 

" H. M. Dawson, Trans. Chem. Soc. 89, 1666 (1906) ; 95, 370 (1909). 
'* Levallois, Bull Soc. Chem. (2) 43, 83, 616 (1885). 
I'' Levallois, ComjJ. Rend., 98, 372, 732 (1884) ; 99, 431, 1027 (1884). 
16 Bechamp, lUd. 99, 1027, 1122 (1884) ; IQO, 279, 368 (1885). 
1' Willstatter & Zechmeister, Ber., 46, 2401 (1912). 
IS Schlossberger, Journ. fiir praU. Chem. 73, 373 (1858). 
19 Lehner, Zeit. fiir angew. Chem., 19, 1584 (1906). 
=» Mulder. Jahr. der Chem., 566 (1863). 
21 Haller, Zeit. fiir Farben Ind. 6, 126 (1907). 



58 REPORTS ON THE STATE OF SCIENCE. 1918. 

Mercerised Cotton. 

It was first observed by Mercer ^~* that cotton fibres shrink when 
they are treated with concentrated solutions of caustic soda. This 
shrinkage has been shown ^ to be caused by the action of internal 
stresses present in natural cotton fibres. If prevented from shrink- 
ing while under treatment with the alkali, the fibres acquire an 
increased lustre. ^"'^ Lange * considered this lustre to be due to the 
smoothness of the surface of the mercerised fibres as compared with 
untreated cotton. Hiibner & Pope ^ suggested that the formation of 
regular spiral grooves in the fibre during mercerisation was the cause 
of the lustre. This theory has been shown ^ to be untenable, Lange's 
theory being substantially correct. The shape of the cross-section of 
the mercerised fibres has been shown to have an important bearing 
on the lustre. '' 

The amount of caustic soda absorbed by cotton during merceri- 
sation has been investigated by several workers. ^^^^^ ^^ Vieweg^^ 
observed change points in the curve of absorption but Miller ^^ found 
the curve to be continuous. Clayton Beadle & Stevens ^^ made some 
interesting observations on the absorption of caustic soda by regener- 
ated cellulose which have an important bearing on this subject. 

Mercerised cotton has properties which difi:er from those of 
ordinary cotton in the following manner : — 

It grinds more pg,sty in the hollander, i''~i'' dissolves quicker in 
solvents, gives a greater yield of benzoyl derivative, ^^ gives nitrates 
more soluble in solvents ^^ but giving less viscous solutions ^^ and 
gives a blue colour with iodine with a less concentrated solution of 
sulphuric acid than ordinary cotton. '' In the last case, the applica- 
tion of tension during mercerisation has been shown to modify the 
reaction. 

All these properties are in agreement with the view that 
mercerisation produces distension of the fibre — colloid. 

Mercerised cotton appears to revert towards its original condition 
on drying,2i ^4 36 ^j. qjj treatment with alcohol.^^ Green^^ considers 
this reversion to be due to anhydride formation, but the author 
thinks it is an ordinary case of gel-dehydration, since the same 
effect is produced by pressure without the application of heat or 
chemical re-agents.-^ A similar change is produced by pressure on 
wet unmercerised cotton,^^ the effect being much greater when 
heat also is applied.^^ ^^ 

The internal structure of cotton fibres,^''-^? gi-^j tjjg internal 
stresses present in them (A 12) are considerably modified by 
mercerisation : these changes persist when the fibres are dried. 

The dyeing properties of cotton,^* ^^ and its re-activity towards 
certain re-agents, are modified in a similar manner to that produced 
by caustic alkalies, when treated with solutions of sulphuric, 
hydrochloric^'' and nitric acids^'^ and zinc chloride.^ * 

(D) Mercerised Cotton. 

' Cross & Bevan, Rcseareheg, I. p. 26. 

- Gardener, Mercerittation. 

^ Mercer, Life and LahourK of John Mercer, Parnell (Longmans, Green), 1884. 

* Mercer, E. P. 13296 (1850). 

« Lowe, E. P. 20314 (1889). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 59 

6 Thomas i: Prevost, D. R. P., 85564 (1895). 

'Harrison, Journ. Soo. IJi/ers J)- Cola. 31, 198 (1915). 

" Lange, Farber ^eitiinr/, 197 (1S98). 

s Hubner i; Pope, Jouni. Soc. C/iem. Ind., 22> 70 (1903) ; 23, 410 (1904). 

'" Hiibner, Ibid. 27, HO (1908). 

1' Gladstone, 'Iraiu: C/iem. Soc, 17, (1862). 

'«Crum, Ibid., 16, 406. 

" Vieweg, Ber., 40, 3S76 (1907) ; 41, :^269 (1908). 

'* Miller, Ber., 40, 4903 (1907) ; 41, 4297 (1909); 43, 3430 (1910).. 

1^ Clayton Beadle & Stevens, Juurn. Soe. Z)i/er.i 4' Coin., 30, 244 (1914). 

•« Briggs, Papier Fabrikant, 5, 2644 (1907). 

" Cross, Papier Ze'tunq, 33, 3246 (1908). 

•s Wichelhaus & Vieweg, Ber., 40, 441 (1907). 

'9 Piest, Zeit fur aiujew Chem., 22, 1221, 2012 (1908). 

^" Berl, Zeitfur Sohii'ss ami Spreiigweiseii, 4, 81 (1909). 

-' Copley, Juurn. Soc. Dyer.^ 4- Coh., 24, 72 (1908). 

-■' Green, ibid. 24, 72 (1908). 

23 Hiibner & Teltscher, Journ. Soc. Ind., 28, 641 (1909). 

-* Miller, Ber., 728 (1911). 

" Hubner, E. P., 12455 (1908). 

»6 Harrison, E. P., 16276 (1908). 

" Palmer, E. P., (1909), September. 

28 Crum, Trans. Chem. Soc, 13, 404 (1863). 

29 Fra)ikel k, Priedlander. MM. d. k. Tech. Gew. Mus, Wien, 326 (1898). 
3" Minajeflf, Zeit. Farhcn. Ind., 1 and 17 (1908). 

" Minajeff, Zeit. fur Farben and Textile Chem., 2, 257 (1903) ; 4, 81 (1905) ; 
6, 309, 345, 15, 233, 16, 252, 19, 309 (1907) ; 7, 1 (1908). 

32 Haller, ibid. 8, 125 (1907). 

33 Haller, Koll. Zeit., 20, 127 (1917). 

3* Justin Mueller, Zeit. fur Farben and Textile Chem., ^, 251, 332 (1904). 

35 Knecht, Journ,. Soc Dyers J,- Cols., 24, 68 (1908). 

36Knecht, ibid.,2i, 107 (1908) 

3? Knecht, ibid., 12, 89 (1891). 

38 Leighton, Journ. phys. Chem.. 20, 32, 188 (1916). 

Hydrocellidose. 

Hot dilute mineral acids hydrolyse cellulose forming a pulveru- 
lent substance termed ' hydrocellulose ' ^"^•' and a sugar having the 
same reducing power and optical activity as glucose.^'' "* 

Denham and Woodhouse^^ by the hydrolysis of methylated 
cellulose have obtained methyl glucoses. This points definitely to 
the conclusion that glucose is formed by the hydrolysis of cellulose, 
although Cross^'-* considers this to be still an open question. 

The aiTthor^^ has shown that hydrocellulose may exist in several 
different colloidal states and has suggested that it is a form of cellu- 
lose containing adsorbed reducing bodies. Guignet's soluble cellu- 
lose-'^ is probably a similar form of cellulose not containing reducing 
agents. 

The action of chemical reagents on a solid structure would 
obviously be to attack the exposed surfaces and dissolve them away, 
gradually reducing the size of the solid particles, with consequent 
modification in colloidal state. 

(E) Hydrocellulone. 

' Cross & Bevan, Cellulose. 

2 Schwalbe, Bie Cellulose, p. 211. 

3 Giiard, Ann. Chem. Phys. (5) 24, ">42-370 (1881). 

4 I'lechsig, Zeit. Physiol Chem. 7. 523 (1883). 
■' Vignon, Comp. Jtend. 126, ^'^-^-^ (1888). 



60 REPORTS ON THE STATE OF SCIENCE. 1918. 

" C. Koechlin, Bull. Soc. Mulhouse, 55 (1888). 

' Cross & Bevan, Journ. Soc. Chem., Ind. 12, 966 (1893). 

« Stern, Trans. Chem. Sue. 67, 74 (1895). 

s Tollens & Murmurow, Ber. 34, 1431-4 (1901). 

1" Morck & Walker, Jm/ni. FranUiri Inst. 136 (1907). 

" Schwalbe, ZeU. fur aw/ew Chem. 20, 2170 (1907). 

'- Buttner & Neumann, ibid. 21- 2609 (1908). 

13 Ost. & Wilkening, Chem. Zeit. 34, 461 (1910). 

'■* Cross & Bevan, Wi Int. Cungress AppVfd Chem. 13, 101 (1912). 

'•'^ Harrison, Joitrn. Soc. Dyers and Cols. 28- 238 (1912). 

i« Willstatter & Zechmeister, Ber. 46, 2401 (1913). 

■' Denham & Woodhouse, Tra/is. Chem. Sue. 1735 (1913): 2357 (1914): 244 (1917). 

>» Cunningham, ibid. 173 (1918). 

'9 Cross & Bevan, ibid. 182 (1918). 

2" Guignet, ComjJ. Bend. 108, 1258. 

-' Fort A: Pickles, Jonrn. Soc. Bi/ers ,!(• Cols. 31, 255 (1915). 

-- Briggs, Jouryi. Soc. Ch. Ind. 78 (1916). 

Oxycellulose. 

Oxidising agents attack cellulose, producing bodies'^^ '' '^"24 gjrai- 
lar in man;)' respects to hydrocellulose, « « 9 lo 24 m 26 jj^ f^^^ .^^ ^.gg^. 
has yet been found which definitely distinguishes between these 
substances. The suggestion has been made^* that oxycellulose con- 
sists of a form of cellulose containing adsorbed reducing substances 
which may or may not be similar to those present in hydrocellulose.^* 
It is interesting to note that oxycellulose is formed by the action of 
light on cellulose."'^ '"* 

Cross and Bevan^' "** observed that bleached cotton retained the 
power of liberating iodine from potassium iodide much longer 
than the presence of a trace of hypochlorite would account for.^** 
They considered that a peroxide was formed. Ditz^^ ^' made a similar 
observation in the action of ammonium persulphate on cotton. This 
effect may be due to adsorption by the fibre-colloid.^^ ^^ 

A similar elfect has been noticed in the action of ozone on 
cellulose.^^ 

(F) Oxycellulose. 

' Cross & Bevan, Cellulose. 

2 Schwalbe. Die Cellulose, pp. 221-257. 

3 Witz, Bull Roueu. 10, 447 (1882) ; H, 2210 (1883). 

* Vetillart, ibid.. 11, 234 (1883). 

* Permetier. ibid., H, 236 (1883). 

6 Schmid, Biurjler's Journ. 250, 278 (1883). 

7 Cross & Bevan, Tram. Chem. Sue. 43, 22 (1883) ; 46, 206, 291, 897 (1884). 

8 Witz & Osmond, Bull. Soc. Chem. 45, 309-15 (1886). 

9 Witz & Osmond, Ber. 19 (3), 318 (1886). 

1" Nastjukcff, Bull Mulhuuse, 62, 493-510 (1892). 

•1 Cross, Bevan, & Beadle, Ber. 26, 2520 (1893). 

1- Bull, Tram. Chem. Soc. 71, 1090-1097 (1897). 

'3 Vignon, Bull Soc. Chem.. (3). 19, 790 (1898). 

" Von Faber & Tollens, Ber. 32, 2592 (1899). 

'5 Bumcke ii Wolffenstein, Ber. 32, 2493 (1899). 

16 Nastjukoff, Ber. 33, 2237 (1900). 

" Nastjukoff, Ber. 34, 719 (1901). 

18 Murmurow, Sack & Tollens, Ber. 34, 1427 (1901). 

" Vignon, Bull Soc. Chem. (3) 25, 136 (1901). 

'» Kurz, Ziet.fur Farb. and Tcrtilchemie, \, 46 (1902). 

21 Vignon, Ball Soc. Chem. (3) 29, 513 (1903). 

" Berl & Klaye, Zcit Schicss and Sprengwesen, 2, 381, 387 (1907). 

" Ditz, Journ. Prakt. Chem. 78, 348 (1908). 



ON COLT-OID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 61 

»* SchoU, Ber. 1312 (1911). 

" Ermen, Jou.ru.. Soe. Dyers and Coh. 26. 266 (1910) ; 27,(1911). 
26 Harrison, Jmrn. S><c. Dijers ami Coh. 28, 359 (1912). 132 

Cellulose Peroxide. 

" Cross & Bevan, Zeit. angew. Chem. 19, 2101 (1906). 

2s Cross, Bevan & Briggs, ibUl., 20, 570 (1907). 

29 Ditz, Chem. Zlet. 31, 833, 844, 857 (1907). 

3" Heinke, ihUh, 31, 974 (1907). 

3' Zimmermann, /Aet. fur anqew. Chem. 20, 1286 (1907). 

^- Ditz, Jouni. prakt. Chem. 78, 343 (1908). 

33 Grandmougin, Chem. Zeit., 32, 242 (1908). 

Cellulose Ozonide. 
31 Doree, Trans. Chem. Soe. 101, 497 (1912). 

Action of Light on Cellulose. 

3* Hartley, Froc. Boy. Soe. B 78- 385 ; 80. 376. 
36 Hartley, Trans. Chem.. Soe. 63, 243 (1893). 
3' Harrison, .Tourn. Dyers and Cols. 28, 225 (1912). 
38 Doree & Dyer, ibid., 33, 19 (1917). 



Cellulose Nitrates. 

When cellulose is treated with a mixture of sulphuric and nitric 
acids, esters are formed containing nitrogen in quantities varying 
with the conditions of treatment.'"^ '' ^ '^ ^^ ^^^^ Many authors^ ^ ^ 
have attempted to classify the products, according to degree of 
nitration, into nitrates of definite molecular composition but there 
seems to be no break in the curve representing the amount of nitro- 
gen introduced by different concentrations of acid." ^^ ^^ The sug- 
gestion has been made'^that nitrocelluloses are adsorption compounds 
but this view does not appear to have been substantiated.^' There 
is little doubt that true esters are formed, but as the cellulose is solid 
during treatment, the reaction must take place from the exposed 
surfaces, whetner external or within the porous structure of the fibre, 
and the degree of nitration must be dependent on the colloidal state 
of the fibre siibstance. 

The viscosity of solutions of nitrocellulose" ^^ '^ ^'^ -° -' vary with 
the conditions of preparation. A nitrocellulose after solution and 
reprecipitation has been shown to give a less viscous solution than 
one diz-ectly dissolved.^^ Similar changes have been observed with 
rubber solutions. 

The behaviour of nitrated cotton towards polarised light has been 

investigated by several authors ^^ ^* ^^ -^ and many interesting points 

brought forward. 

(G) Cellulose Nitrates. 

' Cross & Bevan, Cellulose, p. 38. 
-' Schwalbe. Hie Cellulose, p. 270. 
3 Schonbein, Comp. Rend. 23, 678 (1846). 

* Otto, ihid., 23, 807 (1846). 

^ Crum, Proc. Phil. Soe. Glasgow, 183 (1847). 

6 Eder, Ber., 13, 169 (1880). 

7 Knecht, Journ. Soe. Dyers 4' Cols., 12, 89 (1891). 

* Veielle, Comp. Rend., 95, 132 (1883). 
9 Liebschutz, Mo/i. Sri., p. 119 (1891). 

'» Vignon, Comp. Rend., 126 (1898). 



62 REPORTS ON THE STATE OF SCIENCE. 1918. 

"tunge, Jmirn. Amer. Chem. Soc, 23, 527 (1901). 

'-■ Berl & Klaye, Mon. Sci. (4), 23, 103. 

" Mosenthal, Journ. Soc Chem. Iiid., 292 (1901). 

i< Cross & Bevan, Cellulose (pp. 38-41) Researches, 1895-1900, p. 43: 1900, 3, 
p. 97. 

'^ Saposchnikow, Journ. Russ. Phys. Chem. Soc, 35, 669,(1904) ; 36, 518. (1905) ; 
38, 1186 (1906). 

(See also 7th Internal Cong. Appl. Chem., London, p. 19). 

16 E. Justin Mueller, KoU. Zeit., 2, 49 (1907). 

1' Arthur Muller, ibid., 2, 173 (1907). 

's Mosenthal, Jotirn. Sue. Chem., Ind. 443 (1907). 

'9 Piest, Zeit. angew. Chem., 22, 1215 (1908) ; 23, 1009 (1910). 

'■"> Berl, Zeit. f. Scheiss and Sprengioesen, 4, 81 a909) ; 5, 254 (1910). 

21 Schwartz, Koll. Zeit, 12, 32 (1913). 

22 Ambronn, Koll. Zeit, 13, 200 (1913), 

23 Knecht & Lipschitz, ^oMm. Soc. Chem. Ind. 33, 116 (1914). 

Organic Esters of Cellulose. Gellulose Acetates. 

Cellulose forms esters of acetic acid when treated with acetic 
anhydride in presence of condensing agents.i"^^ tj^q maximum 
amount of acetyl groups which can be introduced without modifica- 
tion of the cellulose complex corresponds to one half of the number 
of carbon atoms present in the cellulose. It is possible to introduce 
more acetyl groups but considerable modification in the cellulose is 
produced. 

The solubility of cellulose acetates and the viscosity^° of its 
solutions varies with the conditions of preparation in a more irregular 
manner than the nitrates. Even under apparently identical con- 
ditions, different results are sometimes obtained. The ease with 
which the colloidal state of the cellulose in cotton fibres is changed is 
possibly the explanation of these differences. 

Cellulose Formate. 

Cellulose forms derivatives with formic acid quite readily in the 
presence of condensing agents.""^^ It has been stated-" that cellulose 
formate is produced when oxalic acid solution is dried on cotton. 

The properties of cellulose formates have not yet been thoroughly 
studied. 

Of other esters of cellulose the following have been prepared : — 

Cellulose propiouate,-i butyrate,^- aceto-butyrate,-^ palmitate,^^ 
phenyl-acetate,22 phospho-formate/^ aceto-nitrate,^* aceto sulphate,^* 
nitro-sulphate,^'^ 27 28 sulphonates, etc. 

Recently, methylated celluloses^"' ^^ have been prepared, and their 
products of hydrolysis carefully studied. Nastjukoff^^ claims to have 
prepared phenylated celluloses. 

(H) Cellulose Acetates. 
' Cross & Bevan, Cellulose, p. 34. 
''■ Schwalbe. Die Cellulose, p. 316. 
3 Worden, Nitrocellulose Industrg, pp. 984-1004. 

* Schutzenberger, Comp. Bend. 61, 488 (1869); 68- Sl-t (1870). 
■■■ Franchimont, Ber. 12, 1264, 1941, 2099 (1879). 

« Cross & Bevan, Trans. Chem.. 5'oc. 57, 1 (1890); 67, 433 (1895) 
' Thiele, Jourii. Soc. Dyers .<• Cols. 24, 294 (1908). 

* Cross & Briggs, ibid. 24, 189 (1908). 

** Schwalbe, Zt-it. angew. Chem. 23, 435 (1910). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 63 

'• Knoevenegal, iMd. 24, 504 (1911). 

" Patents. Compare Suvern, Die hundliche Seide, Berlin (1900). 

" Compare Marsden, Journ. Soo. Dyem cf Coin. 21, 103 (190.5). 

" Compare Worden, Jour». Soc. Chem. Ind. 31, 1064 (1912). 

Celhilose Formate. 

X Berl & Smith, Ber. 40, 903 (1907). 

" Woodbridge, Joiini. Amev. Chem. Soc. 31, 1070 (1909). 

'« Deming, ihid. 33, 1519 (1911). 

" Worden, Journ. Soc. Chem. Ind. 31, 1064 (1912). 

'8 Worden, Nitrocellulose Industry, pp. 1004-1006. 

19 Cross, Trans. Chem.. Soc. 99, 1450 (1911). 

2" Knecht, 7th Int. Cong. Ajrp. Chem., London, 1909. 

" Cellulose Propionate. See refs. 14 & 15. 

*' Cellulose Butyrate. Aceto- But y rate, palviitatc and phenyl-acetate. Hencliel, 
D.R.P. 12817/00 

" Cellulose Phospho-formate. V&reinigle Glanzstof Fahr. E.P. 29246/10; 309/11. 

2< Cellulose Aceto-Nitrate. Berl. & Watson Smith,' Bcr. 40, 903 (1907). 

'^ Cellulose Acetosulphate and Acetobenzoate. Cross, Bevan, & Brigge, Ber. 38, 
1859, 3561 (1905). 

2^ Cellulose Nitrosulphate. Cross & Bevan, Researches, 1900-5, pp. 51-53. 

" Cellulose Nitrosulphate. Cross, Bevan, & Jenks, Ber. 34, 3496 (1908). 

^' Cellulose Nitrosulphate. Hake & Lewis, Journ. Soc. Chem. Ind. 24, 374, 914 
(1905). 

^^ Benzoate. Cross & Bevan, Cellulose, p. 32 ; Researches, I. p. 34. 

3» Methylated Celluloses. Denham & Woodhouse. Tram. Chem. Soc, 1735 (1913) ; 
2357 (1914) ; 244 (1917). 

31 Ethylated Celluloses. Lilienfeld, F.P. 447974 (1912). 

'2 Phenylated Celluloses. Nastjukoff, Journ. Russ. Phys. Chem. Soc. 34, 231, 
505 (1902). Compare Joiorn. Soc. Chem. Ind. Abstracts 1.302 (19C2) ; 414 (1903) ; 
282 (1907). 

Viscose. 

When treated with caustic soda and carbon disulphide cellulose 
forms a xanthogenate soluble in water.^"^ A solution of this sub- 
stance increases in viscosity on standing and eventually sets to a 
jelly. This change is known as ripening and is considered by 
Cross and Bevan to be due to the formation of compounds of 
increasing complexity. This phenomenon appears to be quite 
analogous to the setting of a gelatine jelly, although recent patents^ 
indicate that the oxygen of the air may play some part in it. It is 
interesting to note that if the cellulose is left in contact with the 
caustic soda for some time before conversion into viscose a less 
viscous solution is produced.^ 

(I) Vi.scose. 

1 Cross & Bevan, Cellulose, p. 25 ; Researches, pp. 27, 107. 

- Schwalbe, Die Cellulose, p. 332. 

' Cross, Bevan, & Beadle, E.P. 8700 (1892). 

* Cross, Bevan, & Beadle, Tranji. Chem. Soc. 63. 837 (1893). 

^ Cross, Bevan. & Beadle, Journ. Soc. Chem. Ind. 12, 498 (1893). 

8 Cross, Bevan, & Beadle, Ber. 34, 1513 (1901). 

' Beltzer, A'oll. Zcit. 8, 177 (1911) ; 9, 76, 120 (1911). 

s Courtaulds, GJover, & Wilson. E.P. 13, 005 (1914) ; 14675 (1914). 

9 Cross & Bevan, Researches (1900-5), p. 107. 

Artificial Silk. 

The preparation of artificial silk^ is dependent on the coagulation 
of a cellulose solution, and it is found that the viscosity of the 
solution influences the nature^ ^ of the fibres obtained. 



64 REPORTS ON THE STATE OF SCIENCE. 1918. 

x\n interesting investigation has recently oeen carried out by 
Clayton, Beadle & Stevens on the swelling of artificial silk in caustic 
soda solutions.* ^ It was found that the swelling increased with the 
concentration of alkali up to a certain point and then decreased. 
This change is very similar to that observed by Procter with gelatine 
and hydrochloric acid. Procter's method of investigation cannot be 
applied in this case since the concentration of alkali used is too high. 
It was shown that the addition of sodium chloride to the caustic soda 
diminished the swelling and adsorption of alkali. The author found 
that if the artificial silk was first treated with the caustic soda and 
then with a salt solution the amount of swelling was considerably 
decreased, but practically no caustic soda passed into the salt solution. 
It is, of course, known that sodium chloride ' salts out ' caustie soda 
from solution. 

(J) Artificial SiUi. 

' Suvern, Die Ewiistliche Seide, Berlin (1900). 

' Herzog, Untersuclmng der naturlichen und Kunstlichen, Selden (1910). 

3 Gaidukow, Koll. Zeit., 6, 260 (1910). 

* Clayton, Beadle A: Stevens, S/A Int. cong. Ckem. 13, p. 2.5. 

■'' Clayton, Beadle & Stevens, Jaurn. Soc. Dyers and' Cols., 30i 214 (1914). 

e Ost, Zeit.f. angew. C'liem., 31, p. 141 (1918). 

' Wilson, Journ. Soc. Chem. Ind., 817 (1917). 

Wool. 

The products formed by the hydrolysis of wool have been 
deteruiined,^ but nothing is known of the constitution of the 
substances of the wool fibre itself. The presence of a free amido 
group in the substance of the wool fibre has been discussed from time 
to time without any very definite conclusions being arrived at.^ ^ * i^ 
It has recently been shown that wool fibres are not chemically 
homogeneous, the outer layers being more resistant to the action of 
chemical reagents than the inner parts.'' ^ 

By treatment of wool with solutions of caustic alkalies a colloidal 
solution is obtained,^ which forms precipitates with dyestuffs.*""^* 
These precipitates have been considered to be definite chemical 
compounds. The process of precipitation reminds one more of the 
coagulation of colloidal solutions than of chemical combination. 

The colloidal state of wool fibres is considerably changed by 
boiling in water, the fibres becoming more plastic ; changes, in the 
internal strains are also produced.^ i** 

"When subjected to beating in presence of solutions of soap or of 
acids, wool fibres become matted together, the process being known 
as felting, fulling or milling. For many years felting has been 
considered to be due to the interlocking of the serrations present in 
wool fibres. This theory was supported by the fact that in some 
cases fibres with less serrations felted less easily than others with 
more, and that treatment with chlorine" removed the serrations and 
prevented felting. There are, however, wool fibres having practically 
no serrations which can be felted, although with difficulty, but which 
are also prevented from felting by treatment with chlorine. Another 
theory has been brought f orward^'' that the wool fibres become plastic 
and adhere together when subjected to beating. The fact that a 
fabric made of tightly-spun, straight wool fibres is very much more 
difficult to felt than one made of more loosely-spun material appears 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 65 

against this theory, since the closer contact obtained in the first case 
should assist this adhesion of fibres. 

The author is of the opinion that felting is due mainly to the 
interlocking of fibres caused by the beating of the wool while in an 
elastic condition. Chlorine reduces this elasticity and makes the 
wool more plastic. 

Mechanical pressure produces considerable changes in wool, 
particularly when containing moisture and at a high temperature.' 

The adsorption of acids by wool has been determined by numerous 
workers.^^"^^ The work of Procter {see First Report) on the action of 
acids on gelatine led other chemists^^ to consider that wool formed 
definite compounds with acids. Exactly as in the case of the 
adsorption of caustic soda by cotton and the nitration of cotton, peaks 
were noticed in the curve of adsorption. ^^ In the two examples of 
cotton more recent work has shown that the curves are continuous, 
and it is certain that the same will apply to wool. The author 
attempted to apply Procter's methods to wool, but no results of any 
value were obtained. The amount of swelling in the case of wool is 
very small* compared with that shown by gelatine. The osmotic 
effect which was expected from Procter's theory did not produce any 
changes in volume of the wool fibre ; it may, however, have produced 
a change in the internal stresses present in the fibre, but this could 
not be determined. 

(K) Wool: 

' Abderhalden, Journ. Physiol. Chem. 46i P- 31. 
» Prudhomme, Rev. Gen. Mat. Col. 2U9 (1898). 
' Kann, Fdrher Zeit. 25, 73 (1914). 

* Gabhard, Filrber Zeit. 25, 279, 283 (1914). 

5 Naumann, Zeit. fur angew. Chem. 30, 135, 297, 305 (1917). 
" Allworden, Zeit. angew. Chem. 29, 77, 78 (191H). 
' Champion, Comp. Mend. 72) 330. 

* Knecht &. Appleyard, Journ. Soc. Dyers 4' Cols. 15, 71 (1889). (Dye compounds). 
» Harrison, Proc. Roy. Soc. A. 94. 460 (1918). 

'" Herzoz, Chem. Zeit. 40, 528 (1916). 

" Pearson, Journ. Soc. Dyers S' Cols. 25, 81 (1909). 

'2 Georgievics, Zeit. Physiol. Chem. 87, 669 (1914). 

" Fort & Lloyd, Journ. Soc. Dyers of Cols. 30, 5, 73 (1914). 

'♦ Fort & Lloyd, Ibid. 30, 297 (1914). (Indigo compound). 

'5 Harrison, Ibid. 34, 57 (1918). 

" Gee & Harrison, Trans. Faraday Soc, {April, 1910). 

" Justin Mueller, Koll. Zeit. 114 (1909). 

'« Miller & Tallmann (Strength & Elasticity of Wool). ./. agric. Res. 4, 379 (1915). 

" Hardy, /*i(i. 14, 285 (1918). 

-0 Hartshorne, Trans. Nat. Assoc. Cotton Manuf. 79 194-225 (1905) ; 90, 281- 

319 (1911). 
" Woodmanaey, Journ. Sue. Dyers ^ Cols., 34, 227 (1918). 

Silk. 

A large amount of work has been carried out on the products 
of hydrolysis of different kinds of silk.^-^ The silk fibre in its 
natural condition consists of two substances, sericine and tibroine, 
very similar in chemical nature. The sericine is dissolved from the 
fibroine by the action of dilute alkalies. Attempts have been made 
from time to time to fix this sericine by means of formaldehyde^"* 
in order to avoid the losji in weight of the silk, but liitle is known 
regarding the value of this process. 

20895 C 



66 REPOKTS ON THE STAIE OF SCIENCE. 1918. 

Silk is modified by boiling in water in a similar manner to wool.^ 
The effect of mechanical pressure is also similar with these two fibres. 

Colloid chemical investigations have been made^ with the sub- 
stance present in the glands of the silk worm from which the silk is 
spun. The colloid present in these glands coagulates on standing, 
more quickly on heating or freezing or by treatment with dilute 
acids, a tough gelatinous mass being formed. It is interesting to 
note that the coagulation is accelerated by mechanical strain, and the 
Buggestion has been made*' that the solidification of the silk as spun 
by the silkworm is due to the mechanical strain exerted during 
ejection of the viscous secretion of the silk gland through the 
spinning orifices. This may have some connection with the double 
refraction shown by silk fibres.^ 

(L). Silk: 

' Fischer, 2eif. Physiol Ch. p. 126 (1907). 

2 Abderhalden, Zeit. Physiol Chem. 66, 13—18 & 910 and numerous other articles. 

3 Clavel & Lindermeyer, F.P. 451, 897 (1912). 
« Cardazzi, F.P. 4.57, 326 (1913). 

* Harrison, Proc. Roy. Soc, A-, 94, 460 (1918). . 
6 Foa, Xoll. Zeit. 10, 7—12 (1912). 

' Farrell, Jouni. Soc. Dyers 4' Cols. 70 (1905). (Action of hydrochloric acid.) 

* Sansone, Bev. Gen. Mat. Col. 194 (1911). (Action of formic acid.) 
^ Hohnel, Journ. Soc. Chem. Ind. 2> 172. (Diameter of silk fibres.) 
'" Wardle, Tussicr Silk. 

" Vignon, Recherches sur la sole, Lyon (1892). 

'- Rossinski, Bull, du Labor de la soie, Lyon (1895). 

'^ Franceson, Etudes sur la filature de la soie, Lyon (1890). 

'^ Collomt, Journ. de Physik. (1785). 

'^ Bolley & Schoch, Biyigl polyt Journ. 196 (1870). 

's Cramer, Journ. fur prakt. Chem. 96- 

" Persoz, Mon. Sci. 1, 597. 

IS Mills & Takamine, Trans. Chem. Soc, p. 142 (1881). (Absorption of acids.) 

'8 Silberman, Die Seide. 

Sizing. 

Very little work of any importance has been done with respect 
to the sizing of textile materials, but a considerable amount of work 
has been done on the materials used in this process. The work 
carried out on glue and gelatine has been fully dealt with by Procter 
in the first report. Practically all the work done on starch has been 
considered by Brown^ and by Stocks.- The characteristic blue 
colour produced when iodine is added to starch has been shown to 
be due to colloidal iodine,^ and many other substances have been 
found to give the same reaction.^* 

The changes undergone by starch during boiling are of great 
importance in relation to sizing and finishing and have received 
considerable atteniion.*~i2 The addition of salts has been shown to 
influence these changes.*"^ 

The so-called sizing properties of starch are somewhat obscure. 
The process of sizing is carried out for the specific purpose of assist- 
ing in the weaving of fabrics, and the advantages of any particular 
sizing material can. at present, only be determined by a practical 
test.i^ The relationship between the mechanical properties of the 
sized yarns and the physical properties of the sizing materials has 
never been determined. This is mainly due to the diflficulty of 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 67 

measuring those mechanical properties o£ sized yarns which deter- 
mine their value in weaving. 

(M) Sizhiff, Starch, Sfc. 

' See Brown, First Report, p. 38. 

' Stocks, First Report, p. 46. 

' Harrison, KM. Zeit. 9, .5 (1911) 

* Harrison. Journ. Soc. Dyers 4' Vols., 27 P. 84 (1911). 
■'' Samec, KoUoidchein. Beihe.ft. 3, 123 (lUlI). 

6 Samec, Md. 4, 132 (1912). 

' Samec & Hoeflft, Ihxd. 5, 141 (1913). 

s Samec, ihid. 6, 23 (1914). 

9 Samec & Jencio, "ihld. 7, 137 (191.5). 

'0 Samec, \h\d. 8, 33 (1916). 

" Rakowski, Koll. Zeit. 9, 22.5 (1912); 10, 22 (1912); H, 19, r.l, 269 (1913). 

'3 Harrison, Joiirn. Soe. Bi/ers 4' Cols., 32, 40 (1916). 

" Whowell, Text. hist. Journal 2, 43 (1911). 

'< Barger & Starling, Trans. C/iem. Sor., 441 (1915). 

'* Barger & Field, Trans. Chem. Soe., 1394 (1916). 

Scouring {Soap, &c.). 

The scouring of textiles is mainly a colloid-chemical process. 
In the case of cotton the impurities to be removed are fats and 
colloidal matters usually termed pectic substances. These latter 
form colloidal substances in alkali, by which they are removed from 
the cotton. In recent patents^^ substances of colloidal character, 
starch and albumenoids, are used in conjunction with caustic alkalis 
as scouring agents, and apparently these substances act as protective 
colloids during the scouring process. 

In the case of wool the impurities consist mainly of fat, although 
some protein matters are present in the " suint." The removal oi 
this fat is effected by a dilute solution of soap. 

The nature of the process of scouring has recently been investi- 
gated from th(! colloid-chemical standpoint^'' and numerous important 
points deduced. 

The impurities in silk consist mainly of albumenoid and are 
removed by dilute solution of soap. 

(N) Scouring Soap, S'c. 

' Chevreul, Recherches sur les Corps gras d'origim animale Paris (1823). 

2 Krafft, Ber., 27, 1747 (1894) ; 28, 2566 (1895) ; 29, 1328 (1896) ; 32, 1584, 
1899. 

3 Kahlenberg & Schreiner, Zeit.f. Phy». Ckem., 27, 559 (1899). 

* Cornish, ihid., 31, 42 (1899;. 

* Donnan, ibid., 31, 44 (1899). 

6 Donnan & White, Trans. Chem. Soc., 1668 (1899). 

' Browden, ihid., 191 (1899). 

8 Goldschmidt, Seifenfahr., 1247 (1902). 

'Smits, Zeit.f. Ph.y.<t. Chem. 45, 608 (1903). 

'" Leimdorfer, Seifenseider Zettung Ausgherg, (1906). 

" Meyer, Schaeffer k Terroine, Comp. Rend., 146, 484 (1907). 

'= Spring, Koll. Zeit., 4, 162 (1909); 6, H, 109, 164 (1910). 

'» Leimdorfer, Kolloidehem. Beihefte, 2, 243 (1910J. 

'1 Donnan & Potts, Koll. Zeit, 7, "208 (1911). 

'^ Reychler, ihid., 12, 18, 277 (1913) ; 13, 252 (1914). 

isArndt & SchifE. Kolloid. Beihe.fte, 6, 201 (1914) 

" Kurzmann, ibid, 5 433 (1014). 

'8 McBain, Tram. Faraday Soc, 9, 99 (1913). 

20895 C 3 



68 KEPOUTS ON THE STATE OF SCIENCE. 1918. 

19 Fischer & Hooker, Koll. Zeit. 18, 129 (1916). (Caeein Solutions.) 
'"Shorter, Journ. Soc. Dyers # Cols., 31, 64 (191.5); 32, 90 (1916); 34, 136 

(1918). 
=' Shorter & Ellingworth, Proc. Boy. Soc, A- 92, 232 (1916). 
" Pickerinff, Trans. Chem. Soc, HI, 96, (1917). 
" Shorter & Harrison, Journ. Soc Dyers * Col*., 34, 163 (1918). 
2< McPherson k Keys, E.P., 5620 (1909) ; 20089 (1909) ; 8478 (1915). 
^' McBain & Taylor, Ser. 43, 321 (1910). 
26 McBain & Taylor, Zeit. jjliys. Chem., 76, 179 (1911). 
" Bowden, C/iem. Soc Trans., 99, 191 (1911). 
'8 McBain, Cornish & Bowden. ibid. IQl, 2042 (1912). 

29 Bunbury & Martin, ibid. 105, 417 (1914). 

30 McBain & Martin, ibid. 105, 957 (1914). 
3' Lairg, ibid. 113, 435 (1918). 

32 McBain & Bolam, ibid. 113, 825 (1918). 

Dyeing. 

The large amount of work carried out on dyeing has already been 
fully considered by King in the first report. The electrical theory 
of dyeing has recently been discussed at some length.^ In its pre- 
sent condition^ four factors are taken into account. 

1. Molecular movement, by which dye molecules or particles 
transport themselves on to the fibre or into its pores. In true solu- 
tion, this process is usually known as diffusion and must be taken 
into account in all theories of dyeing. In colloidal solutions the 
same thing occurs but to a less extent. 

2. The electrical charge on the fibre and on the dye. The poten- 
tial of this charge has been measured under several conditions as 
regards nature and concentration of added electrolytes. The nature 
of this contact potential has received much discussion ; some 
chemists consider it to be due to residual valency. The opposite 
view that valency is the direct result of the electrical construction of 
elements is more likely to be true. In any case, Bragg's models of 
crystals show that the surfaces of solids must behave differently from 
the bulk of the material. 

3. The size of the pores in the fibre. 

The presence of these pores has been directly proved by ultra- 
microscopic examination and indirectly by the fact that colloidal 
solutions can penetrate to a considerable extent into the fibres. The 
idea that dyes are imbibed into the cavities and pores of fibres by 
capillary attraction was put forward by Crum more than 50 years 
ago. The manner in which the dyes were fixed in those pores was, 
however, not explained by Crum, but has been explained as a case of 
electrical coagulation. 

The increased dyeing produced with cotton on mercerisation has 
been shown to be due to changes in the colloidal state of the fibre as 
well as electrical charge. The effect of drying on mercerised cotton 
is to reduce its dyeing capacity ; this has been explained as being 
due to reversion of the changes produced by mercerisation. 

4. The size of the dye particles. 

It is obvious that the extent to which dye particles can penetrate 
into porous substances must depend on their size. The rapidity of 
coagulation is also dependent on the size of the particles. 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 69 

By the inclusion of these four factors, the electrical theory appears 
to explain most cases of dyeing ; its value is recognised mostly in 
the case of direct colours where chemical theories have failed. 

Printing. 

The printing of textile fabrics is carried out by applying a viscous 
solution by means of an engraved roller to the fabric. Many interesting 
colloid-chemical phenomena are met with in the preparation of the 
viscous printing pastes. Even to-day there is a considerable amount 
of secrecy exercised in the preparation of these pastes, partly as 
regards the materials employed, but more particularly in the manner 
of mixing them. There is little difficulty in ascertaining the in- 
gredients by chemical analysis, and by the help of colloid -chemistry 
the order in which the ingredients must be mixed can readily be 
decided. Materials which precipitate one another should first be 
mixed with the protective colloid, starch, tragacanth, &c. 

The subsequent fixation of the printing colour by steaming, par- 
ticularly in the case of non-mordant dyes, has been shown to be due 
to the swelling of the fibre by the action of the steam.'' 2«""4 -pj^Q 
fixation of colours from pastes containing both colour and mordant is 
undoubtedly due to coagulation, as the result of reduction in the 
protective power of the colloids at high temperature.*^""'*™ ^ 

Finishing. 

The finishing of textile fabrics is an art to which very Itttle science 
has been applied. The effects of the mechanical treatments to which 
fabrics are subjected during finishing' have only recently been 
investigated.* The main factors are mechanical pressure, heat and 
moisture. The effect of moisture is to increase the degree of swelling 
of the fibre, and this is greater the higher the temperature. Pressure 
decreases the swelling in the direction at which it is applied. Per- 
manent finishes are produced by processes which reduce the swelling 
capacity of the fibre colloids. 

(0) Dyeing, 

' Compare King, First Report, p. 20. 

' Harrison, Journ. Soc. Byers and Cols., 27, 279 (1911). 

' Harrison, ibid. 34. 97, 127 (1918). 

< Craven, ibid. 34, 128 (1918). 

» FoTt, ibid. 34, 124 (1918). 

6 Hallcr, £oU. Zeit., 23, 100 (1918). 

(P) Printing. 

Compare First Report Article by Stocks. 46-78. 

> Justin Mueller, Koll. Zeit., 5, 2S3 (1909). 

» Justin Mueller, 7, 40 (1910). 

» Harrison, Koll. Zeit., 9. 5 (1911). 

« Haller, Kolloidchem. Beihefte, 8, 1 (1916). 

* Haller, Koll. Zeit., 23, 100 (1918). 

(Q) Finishing, 

' See Article in Journ. Sue, Dyers and Colourists, 29 117 (1913) 
' Harrison, Textile Inst. Journal (1916). 

20895 C 3 



70 REPORTS ON THE STATE OF SCIENCE. 1918. 

REPORT ON THE PART PLAYED BY COLLOIDS IN 
AGRICULTURAL PHENOMENA. 

By E. J. RuSvSELL, D.Sc, F.R.S., Director of the 
RotliaTnsted Experimental Station. 

Agricultural chemists only slowly recognised the part played 
by colloids in the soil. For many years the soil was regarded as 
a mass of ciystalloid mineral matter, and in discussions of its 
properties it was treated as if it were sand mingled with certain 
soluble salts and organic matter. Sand cultures were commonly 
adopted in pot work; sand particles were used in experiments on 
the physical properties of the soil ; and in the early attempts at 
mathematical analysis the particles were supposed to be spherical 
and impenetrable, though this assumption was recognised as an 
approximation only. As experimental results and deductions 
accumulated, it became obvious that there was a wide discrepancy 
between the properties expected and those actually found in 
natural soils. It therefore became necessary to re-examine the 
fundamental propositions. 

The first demonstrations of the unsoundness of the old views 
came from the Dutch investigator van Bemellen. It had long 
been known that soil possessed the remarkable property of absorb- 
ing certain soluble substances from their solutions : ammonia was 
taken from ammonium sulphate solution, potash from potassium 
sulphate, and so on. It was this property that justified the use 
of soluble salts as artificial fertilisers. The first explanation was 
offered by Way, who supposed that the process was a simple 
chemical reaction of the double decomposition type, and he 
assumed the existence in the soil of a series of reactive silicates in 
order to account for the observed phenomena. Subsequent 
wa"iters, adopting the simple expedient of keeping away from the 
soil, elaborated the properties of these double silicates ; and when, 
at a later date, mineralogists directed attention to the zeolites, 
some of the agricultural chemists assumed that these substances 
existed in quantity in the soil and were the reactive constituents 
in question. 

Shortly after Way had offered his chemical hypothesis Liebig 
advanced a physical explanation. He supposed that soil had 
some power of attracting dissolved salts similar to the power 
possessed by charcoal for condensing g-ases. Only the substances 
physically held in the soil were considered of immediate value to 
the plant, although the chemically combined substances might be 
a reservoir in maintaining supplies. 

Further investigations showed that neither explanation was 
quite sufiicient : Knop therefore combined the two hypotheses and 
explained the absorption of acids as a chemical combination with 
iron or aluminium oxides, and the removal of bases partly as a 
physical attraction and partly as a chemical combination with 
silica or double aluminium silicates. But the compromise was 
not very satisfying and aroused little enthusiasm ; moreover, it 
did not help to account for the ever increasing number of 



1 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 71 



apparently abnormal phenomena. Later on van Bemmelen proved 
that the phenomena were precisely similar to those shown by 
colloids, and argued that the soil must be treated as a colloid. 
This view was generally accepted by those who read his papers. 
Unfortunately, van Bemellen's work was published in German, 
and the translation from his own language was not altogether 
happy — rather giving the impression of a long drawn tedious 
memoir on an unimportant subject. A good English translation 
is very desirable : the papers belong to the classics of agricultural 
chemistry. Van Bemellen did not at once arrive at the colloid 
explanation ; he first accepted Way's chemical explanation, and, 
indeed, devised a method for estimating the double silicates 
present. Later on, however, he made extensive studies of 
absorption by simple gels, silica, alumina, ferric hydroxide, tin 
hydroxide, etc., and found it closely to resemble absorption by 
soils : other studies of colloids were made, and in each case the 
similarity to soil phenomena was so close as to leave no doubt that 
soil was essentially a colloid and soil absorption simply a mani- 
festation of its colloidal properties. 

This new idea was soon found to explain many of the old dis- 
crepancies. Chemists had several times attempted to bring 
the phenomena of absorption equilibrium into line with those of 
chemical equilibrium, but the equations would not fit except for 
a narrow range of concentrations. 

When, however, the adsorption formula is used, a much closer 

fit can be obtained : Wiegner has gone over the recorded data and 

shown that they all agree with the ordinary equation, 

V ' 

I = KcF 
m 

the constants having the following values : — 



Absorbent. 


Solute. 


K 


1 
P 


Worker. 


Garden soil 


NHjCl 


0-0948 


0-039 


1 Henneberg and 


;, ,} ... ... ... 


NHjCl 


0-131 


0-424 


/ Stohmann. 


Nile sediment 


NHjCl 


0-489 


0-399 


Armsby. 


Permutite ... ^ ( 


NH4CI 


2-823 


0-398 


Wiegner. 


Sodium zeolite }■ artificial -! 


CaCla 


2-487 


0-317 


Armsby 


Zeolite ... J I 


LiCl 


24-419 


0-414 


Campbell. 


Soil 


NH4OH 


0-0994 


0-434 


1 


„ ... ... ... 


NH40H 


0-147 


0-461 


!- Brustlein. 


„ 


NH4OH 


0-054 


0-386 


i 



It is still, however, necessary to account for the fact that the 
absorbed bases displace an equivalent amount of some other bases 
from the soil — a procedure which would be unnecessary if nothing 
but adsorption were involved. This is done by supposing that 
only the hydroxide is absorbed : the acid radicle in general is 
not: it therefore dissolves out some of the bases from the soil. 
As this is a purely chemical reaction the amount of base brought 
out is equivalent to the acid set free, i.e., to the amount of base 
adsorbed. 



20895 



C 4 



72 EEPORTS ON THE STATE OF SCIENCE. 1918. 

Tliis view is found to account for all the phenomena fits yet 
recorded. Moreover, it explains the difl&culties that have 
attended the study of the soil solution or the liquid phase in the 
soil. Chemists now realise that the colloids profoundly affect the 
composition of the liquid phase, and they are devoting consider- 
able time and ingenuity to the problem of extracting typical 
samples for investigation. Centrifugal methods have been tried, 
but they are troublesome in application. Displacement methods 
would be easier if one could be sure that the adsorption relation- 
ships were not being disturbed. Morgan claims that paraffin 
oil is both effective and simple in use. A pressure method is in 
use in Eamaun's and also in van Zyl's laboratories, especially for 
soils containing much clay or humus : 3 kgms. of soil are sub- 
jected to a pressure of 300 kilos per sq. cm. In view of the 
great importance of the soil solution in the nutrition of plants, it 
is a matter of vital necessity to discover the laws governing its 
composition, the influence of manuring, climote and soil 
treatment. 

Thus it is known that sodium salts liberate potassium from the 
soil : lime also has the same effect. Regarded as adsorption 
effects the phenomena are much easier to explain than as simple 
chemical reactions. The technical importance of a full under- 
standing of the phenomena is considerable. There is, however, 
a school of chemists who regard the whole phenomena as chemical, 
and adhere to the hypothesis of reactive zeolites : Gedrortz in 
Russia, and von Rothmund and Kornfeld in Germany. 

Tlie action of Acids on the Soil. 

Agricultural chemists have long hoped that soil analysis might 
guide the farmer in drawing up a system of manuring. Unfortu- 
nately, this hope has proved largely illusory ; the problem is 
complicated by the fact that at least five or six factors enter into 
soil fertility, of which the chemical composition of the soil is 
only one. But there is another source of trouble well recognised 
by agricultural chemists : the selection of a method for the ex- 
traction of the plant nutrients in the analytical process. 

The first methods, founded wholly on mineral analysis, 
involved the use of strong acids and proved of little value in 
this country. A marked improvement was effected when dilute 
acids were substituted for strong acids, biit many anomalous 
cases still arose : in particular, no- two acids ever gave the same 
result, nor even did different concentrations of the same acid. 
The underlying assumption always was that the soil was a mass 
of mineral fragments with the phosphates, etc., in the ordinary 
mineral form. All attempts to interpret the action of dilute 
acids on soil phosphates as an ordinary' chemical reaction failed. 

Russell and Prescott have studied the reaction between dilute 
acids and the phosphates in the soil and find that it can be inter- 
preted satisfactorily as a simple solvent followed by an 
adsorption. The solvent action is practically the same for nitric, 
hydrochloric and citi'ic acids of equivalent strengths, and appears 
to be the normal action of an acid on a phosphate. The reverse 



I 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 73 

reaction is the typical adsorption shown by colloids, and can be 
expressed by the equation which has been found tO' fit so many 
of them. It is considerably influenced by the acid, being' greater 
in the presence of the mineral acids than of the organic acids. 
The amount of phosphorus compound actually brought out is the 
difference between the direct and the reverse action. Thus, 
hj'drochloric acid dissolves out a certain amount of phosphate, 
but considerable adsorption takes place, so that the net amount 
left in solution is only small. Citric acid dissolves out the 
same amount of phosphate, but there is much less adsorption, 
and therefore the amount left in solution is markedly greater. 
The difference between the various dilute acids lies not in their 
solvent power, which is similar for all, but in their influenc-e on 
the adsorption process. The observed net eft'ect of the acid on 
the soil is therefore expressed by the ordinary adsorption curve. 

The reaction between dilute acids and soils thus appears to be 
essentially a displacement of absorbed material by something 
which is itself absorbed ; and it falls into line with other displace- 
ments from colloids. 

If this view is correct, it follows that acids need not be used in 
soil analysis, at any rate for the extraction of bases : any agent 
capable of being absorbed by the soil would serve equally well. 
Eamann has used a solution of ammonium nitrate and finds 
it dissolves at least as much potassium, calcium, etc., as an acid, 
and in some respects is more satisfactory. This method of 
extracting the bases from soils promises to' be useful and to clear 
up many of the difficulties in soil analysis. 

The icater relationships of soils. 

The earlier soil physicists, regarding soil as a mass of mineral 
matter, began their studies of the water relationships of soils by 
treating soil as a mass of sand, or, in mathematical analysis, of 
small bullets or marbles, and investigating the distribution of 
water by surface tension. The conclusions obtained were not 
wholly in accordance with facts. The facts observed in the 
evaporation of water from soil were particularly difficult to fit 
in with expectations, and numerous breaks in the curves seemed 
to indicate the existence of a variety of critical points and 
co-efficients. Keen has shown, however, that the phenomena 
become much clearer when regarded as colloidal effects. He 
found that the relationship of water to soil differs considerably 
from its relationship to sand. The evaporation of water from 
sand, silt, china-clay, and ignited soil proved to be relatively 
simple, and could be explained by the knoAvn laws of evaporation 
and diffusion. But the evaporation of water from soil could not: 
it was more complex. Instead of the simple proportionality 
between water content and time observed in the case of sand, the 
curves for soil were more exponential in type. The difference was 
traced to the soil colloids, and it disappeared when the soil wa.'i 
ignited and the colloidal properties lost : the curve then becam© 
identical with that obtained for sand. The influence of the 
colloids has so far only been expressed empirically, but it is 



74 REPORTS ON THE STATE OF SCIENCE. 1918. 

probably connected with the relation between vapour pressure 
and moisture content. But there is clearly something else at 
work, for the curve is not of a simple exponential type. It is 
necessary to allow for another factor : the effect on the rate of 
evaporation of the water surface in the soil, which obviously 
diminishes in area as evaporation continues. 
The equation finally developed by Keen is : — 

^^^ ( v^^o + ^) (^'^^^ (^^ + ^) - i°°« ^)' 

dw 

where = rate of evaporation. 

dt 

w = percentage of water present by weight. 
s = specific gravity of the soil. 
A and K = constants. 

This relationship holds without any break, proving that all the 
water in a normally moist soil is held in the same way without 
change in physical state. At one end of the curve the water is 
more easily given up than at the other, and in the competition for 
water between soil colloids and plants or micro-organisms some 
kind of equilibrium may be attained under definite conditions : 
this equilibrium is the " wilting point " of the physiologist. On 
this view the other constants and critical points that have been 
indicated by various investigators are all equilibrium points and 
do not represent breaks in the condition of water in the soil. 

The retention of liquid water by soil, or, in other words, the 
resistance to drainage, is no doubt influenced by soil colloids. 
Attempts have been made by Alway and McDole to trace some 
connection between the amount of water absorbed by dry soil 
from a moist atmosphere and its water-holding capacity : in so 
far as these phenomena are related it is probably through their 
relationship to the soil colloids. The influence of salts on the 
permeability of soil to water, which is probably as much physical 
as chemical, has been studied by Hissink. 

Soil Acidity. 

It has long been known that some soils are acid to litmus paper, 
but become neutral on the addition of calcium carbonate. Acidity 
is not tolerated by most cultivated plants, and the agriculturist 
has therefore to guard carefully against it : the problem is one of 
high technical importance. 

The older chemists took the obvious view that acidity was due 
to some .special soil acid or acids, to which various names were 
given : humic acid, ulmic acid, crenic acid, apocrenic acid, etc. 
But no acid satisfying the modern chemist could be isolated, and 
when the colloid conception was introduced Cameron pointed out 
that the phenomena could all be explained as simple colloidal 
manifestations and did not require the assumption of soil acids 
at all. It was only necessary to suppose that the soil colloids 
absorbed the base more readily than ih© acid from blue litmus 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 76 

and the whole phenomena are explained. In support of this 
view Cameron showed that cotton and other absorbents behaved 
exactly lihe "acid" soils, slowly turning blue litmus red; the 
phenomenon was therefore a general property of a class of 
absorbents. 

Baumann and Gully applied this idea to the case of peat and 
showed that it fully explained all the known facts. 

In the first instance they pointed out that it was not necessary 
to assume that the " acid " was a decomposition product because 
the original sphagnum was almost as " acid " as the peat. 

Secondly, the acid if it exists must be insoluble. because the 
water extract of the peat is practically neutral to litmus. 

It must, however, be very potent because solutions of neutral 
salts such as calcium chloride, sodium nitrate, etc., are decom- 
posed with liberation of free hydrochloric and nitric acids when 
treated with peat or sphagnum. 

Baumann and Gully argue that no acid of this character is 
known to chemists, and it involves less strain to conceive of a 
physical adsorption of the base from the dissolved salt with 
liberation of the acid than to imagine an insoluble organic acid 
capable of decomposing simple salts in solution. 

The view that acidity of the mineral acid soils is due to pre- 
ferential absorption of the base was developed by Harris in an 
investigation of Michigan soils. The phenomena are substan- 
tially the same as for peat : the soil turns blue litmus red ; an 
aqueous extract is neutral, while an extract made with a solution 
of a salt, e.g., calcium nitrate, is acid. We must therefore 
assume either an insoluble but very potent mineral acid, or a 
preferential absorption of the base over the acid. The latter is 
indicated because, as in the case of peat, the amount of acid 
liberated from equivalent quantities of different .salts is not the 
same, as it should be in a chemical reaction. 

Daikuhara has applied this view to the case of the acid mineral 
soils of Japan and Korea, but he has modified the explanation 
and made it more easily intelligible to the chemist, who finds it 
difficult to understand why an unparalleled physical decomposi- 
tion of a simple salt should be accepted, and the assumption 
of a difficultly soluble but potent acid rejected. Daikuhara shows 
that the development of acidity in the salt solution is due to an 
exchange of bases and not to simple absorption of the base from 
the salt. If the acid solution is analysed it is found to be really 
a solution of an aluminium salt: aluminium being given up 
from the soil in amount approximately equivalent to the base 
absorbed. Aluminium salts, as is well known, turn blue litmus 
red, and therefore are indicated as acids. The phenomenon is 
still essentially an absorption, but the seat of the reaction is 
located. 

This view is supported by Rice's experiments, which have 
demonstrated the substantial identity in hydrogen ion concen- 
tration of a solution of aluminium nitrate and the solution 
obtained by treating an " acid " soil with .potassium nitrate 
solution. 



76 REPORTS ON THE STATE OF SCIENCE. 1918. 

Eamann adopts this view and gives up the expression " acid 
soils," using instead " absorptiv ungesattigte Boden." Kappen 
confirms the ohservations without entirely accepting the 
explanation. 

The p^hysical explanation of acidity has not passed unchal- 
lenged. Eindall of Helsingfors, Sven Oden of Upsala, Tacke 
and Ehrenberg have each argued in favour of definite humic 
acids in peat. Truog finds, in the case of mineral soils, that 
equivalent amounts of different bases are required to neutralise 
the acid properties of the soil — which, if generally true, would 
be easier to explain by assuming an acid than an adsorption. 

It is always possible that both factors are at work. Evidence 
has been adduced by Christensen and by Schollenberger to show 
that acidity and base-absiorbing power are not quite the same 
thing. Still more significant, measurements of the hydrogen ion 
concentration of soil extracts have been made, and show definite 
acidity. 

Pan foTTnation. 

A pan is a layer ol hard impermeable rock that gradually 
forms below the surface of the soil under certain conditions. Its 
effect is to cut off the soil above from the material below, and 
therefore to modify profoundly the movements of water and air, 
leading often to swampy conditions. The effect on vegetation 
becomes so marked that in agTicultural practice the pan has to 
be removed, often at considerable trouble and expense. 

The conditions determining the formation of pan seem to be a 
supply of organic matter, permeability of soil, low content of 
soluble mineral matter, and absence of calcium carbonate. These 
conditions occur most frequently on light sandy soils where, for 
some reason, the water is held sufficiently near the surface. ' 

The older chemists explained the phenomena on purely 
chemical lines; it is unnecessary to go into the details of the 
various hypotheses put f oa;ward : in the main they involved 
alternate reductions and oxidations, or else solution in carbonic 
acid, and subsequent deposition. These hypotheses broke down 
on further examination, some necessary links failing to be 
realised when the experiment was made under natural conditions. 

Eecent workers, therefore (Munst, Ramann, Morison, Sothers | 
and Stremme) regard the whole process as a formation first of 1 
a "sol " and then of a " gel," and Morison and Sothers suggest .1 
the following as the most probable course of events. '" 

It is well known that " sols " change to " gels " in presence ol 
small quantities of electrolytes, and conversely " gels " often 
change to "sols" when electrolytes are removed. In normal 
s.oils the conditions are favourable to gel formation, but when in 
these particular soils the upper layer of sand becomes denuded of 
its soluble material by the persistent washing of rain water, the 
conditions become fajvourable for the formation of sols of ferric 
hydroxide and of humus — or feiTic humate, if one likes to put it 
in that way. Morison and Sothers actually obtained such 
sols* by persistent washing of ferric-humus gels. 

* As might be expected these did not give the ordinary iron reactions. 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 77 

As the sol is woshed down most of it passes to the permanent 
water level, where it remains and accumulates, ditt'usion being 
practically non-existent. During the dry months a certain 
amount of dessication takes place, involving a deposition of 
the sol as a gel : there is also a certain amount of transformation 
of sol to gel through the presence of electrolytes in the ground 
water.* Some of the humus gels become oxidised, some of both 
humus and ferric hydroxide g'els change their colloidal properties 
in other ways. Wlien wet weather comes on again it is no longer 
possible for the whole of the deposited gel to change back to a sol. 
Deposition has begun, and tlie place where this happened serves 
as a seat of further action. 

This view seems more in accordance with the facts than the 
older one, in that it does not involve any unproved assumptions — 
such as reduction of ferric to ferrous iroai and presence of ferrous 
iron in the pan. 

Flocculation and DefiocculaUoii. 

Clay possesses well marked colloidal properties. If rubbed 
with water it becomes plastic, sticky and impervious : it shrinks 
on drying- and absorbs heat : on moistening, however, the process 
is reversed and there is considerable swelling and evolution of 
heat. The importance of these observations is equally great in 
agriculture and in the ceramic industry. 

Two hypotheses have been put forward to account for plasticity. 
Ro'hland attributes it to hydrated colloids present in tlie clay : 
Atterberg to minute flake-like particles which are able to slip 
over one another without difficulty. 

Another property of clay is ot great importance to agriculture, 
and hais received much attention from agricultural chemists. 
Addition of a trace of electrolyte — ^acids or saltsi — to puddled 
clay causes considerable change in properties : the temporary loss 
of plasticity, impermeability and the power of remaining long 
suspended in water without settling ; the clay is now said to be 
flocculated. The change can be watched if a small quantity O'f 
any floeculating substance is added to the turbid liquid obtained 
by shaking clay with water; the minute particles are then seen 
to unite to larger aggreg'ates which settle, leaving the liquid clear. 
There is, however, no permanent change, deflocculation takes 
place, and the original properties return, as soon as the flocculat- 
ing agent is washed away. Alkalis (caustic soda, caustic potash, 
ammonia, and their carbonates) produce tlie reverse effect : they 
deflocculate clay, intensifying its stickiness and impermeability, 
and causing it to remain suspended in water for long periods. 

These properties are of considerable importance in devising 
schemes of manuring for soils : it is obvious that alkaline sub- 
stances are to be avoided on clay soils, however rich they might 
be in plant nutrients, as they would prodiice undesirable 

* Ramann lays stress on this, Morison and Sothers do not because their sols 
were very stable in presence of electrolytes. 



78 REPORTS ON THE STATE OF SCIENCE. — 1918. 

physical effects. On tlie other hand, slightly acid substances 
such as superphosphate have no bad effects, but rather the reverse. 

Clay is thus an electro-negative colloid, its reaction probably 
being conditioned by a trace of potash liberated by hydrolysis. 
It shows the general properties of electro-negative colloids as 
elucidated by Schulze and by Hardy : thus it is flocculated only 
by a solution containing ions or particles of opposite electrical 
sign, and the extent of flocculation increases rapidly with the 
valency and concentration of the ion. No quantitative relation- 
ships, however, could be found by Hall and Morison. 

Pickering throws over the electrical hypothesis and attributes 
flocculation to a combination of the clay with the flocculant and 
the solute, whereby the aggi-egation of molecules increases so 
much that it loses its power of Brownian movement and soon 
settles. 

Other effects of Colloids. 

Various obscure changes are brought about on drying the soil. 
There is a marked increase in the proportion of water-,soluble 
material, and, as Buddin has shown, in the ease with which 
nitrates are formed. Changes in the micro-organic population no 
doubt account for some, btit not all, of these effects, and the 
simplest explanation is to^ attribute them to the changes in the 
colloids. Again, soil has a remarkable power of decorn^osing 
liydrogen peroxide, which is affected by small quantities of 
ivarious substances, and may be a colloidal phenomenon. The 
decomposition of cyanamide in the soil has been attributed to 
colloids. 

The influence of Colloids on Bacterial and Plant Life. 

Plants and bacteria draw from the soil their water and their 
nutrient salts, and are therefore profoundly affected by anything 
that retards delivery of these essential substances. Inasmuch as 
colloids possess markedly absorbent powers they might serve as 
reservoirs to protect against loss by evaporation or leaching, or, 
on the other hand, they might actually compete against the plant 
and hold some of the supplies the plant ought to obtain. 

As yet there is insufficient experimental evidence to show how 
the various factors are likely to interact. Fortunately ecologists, 
both in this country and elsewhere, are fully alive to the possi- 
bilities : Gola has discussed the influence of the colloidal complex 
in determining plant habitats, and Sohngen its effects on the 
activities of micro-organisms ; an illuminating resume by Cavers 
has also appeared. It is interesting to note tliat soils destitute 
of colloidal properties are often infertile. 

The EstiTnation of Soil Colloids. 

Many efforts have been made to estimate the amount of colloidal 
matter in the soil. They fall into^ two groups based on the 
absorption of dye stuffs and of water vapour respectively. 
Methods based on the absorption of dye-stuffs have been elaborated 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 79 

by Sjollemo, Endell, Ashley, Konig, Hasenbaumer and Hassler, 
Hanley and Tadokoro, the last named giving other references 
also. Methods depending on the absorption of water vapour have 
been suggested by Mitscherlich. Different methods do not give 
altogether concordant results, nor is it to be expected that they 
should; it is highly improbable that any sharp dividing line 
exists in the soil between the typical colloids and the typical non- 
colloids ; intermediate substances are to be expected showing 
colloidal properties only to a slight extent. It is certain, how- 
ever, that the finer particles of the soil — the clay and fine silt — 
show much more marked colloidal properties than the coarser 
particles — the coarse silt and the sands. 

The Constitution, of tlie Soil. 

Soil consists mainly of disintegrated and decomposed rock frag- 
ments of all sizes, varying from 1 mm. diameter downwards; these 
may be said to constitute its skeleton. Intimately mingled with 
these are the decaying remains oi past vegetation. It seems 
necessary further to suppose that the particles are coated with a 
gel composed of silica, oxides of iron and aluminium, soluble 
organic matter, and a smaller quantity of lime, magnesia and 
potash, traces of ammonia, etc. : this gel being spread relatively 
more thickly on the small particles than on the larger ones. This 
view of the constitution of the soil fits in with the known facts, 
and it has the further advantage of offering a definite starting 
point for further investigations. 

Bibliography. 

Gedroitz, K. K. (Reprints), Chem. Soc. Abstracts, 1918, i. 519 and ii. 364. 
ROTHMDND, v., and KORNFELD, G., Zeitsch. Anorg. Ohem. 1918, 103j 129-163. 

I. — Soil Absorptions. 

Way, J. T., 'On the Power of Soils to Absorb Manure," Journ. Roy. Agric. Soc, 

1850, xi. 313-79 ; ib'd. 18.53, xiii. 123-43. 
LiEBiG, Justus, ' Natural Laws of Husbandry,' 1863. 
Knop, 'Lehrbuch der Agrikultur Chemie,' Leipzig, 1868. 'Die Bonitirung der 

Aokererde,' 1871. 
Bemmelen, Jakob M. van, ' Die Absorptionsverbindungen und das Absorptions- 

vermogen des Ackererde,' Landw. Versuchs-Stat. 1888, xxxv. 67-136. 'Das 

Absorptionsvermogen der Ackererde,' ibid. 1878 (23). 265-304. ' Die Absorption 

von VVasser durch Ton,' Zeit. Anorg. Ctiem. 1904, xlii. 314-24. 
WiEGN'ER, Georg, ' Zum Basenaustauscti in der Ackererde,' Journ. f. Landw., 1912, 

Ix. 110-150, 197-222. 
Hager, G., J. Landw., 1917 (65)) 245-311 (a paper on the absorption of lime by 

soil). 

II.— The Soil Solution. 

Morgan, J. F., Soil Science, 1917 (3), 531. 

Ramann. G.. Marz, S.. and Bauer, ri.. Int. Mit. Bodenkunde, 1916 (6), 27. 

Zyl, J. P. VAN, J. Landw., 1916 (d4). 201. 

NOLTE, O., ibid., 1917 (65), 1. 

III. — Action of Acids on Soil. 
Russell, E. J., and Prescott, J. A., ' The Reaction between Dihite Acido and the 

Phosphorus Compounds of the Soil,' Journ. Agric. Sci., 1916 (8), 65-110. 
Hanley, J. A., Nature, 1914 (93), 598. 
KCllenberq, Jahrbucher Agric. Chem., 1865 (8), 15. 



80 HEPOHTS OS THE STATE OF SCIENCE. 1918. 

IV. — Water Relationshiin. 
Keen, B. A., ' The ETaporation of Water from Soil,' Journ. Agric. Sci., 1914 (9), 

456-75. 
Alway, F. J., and McDole, G. K., Journ. Agric. Research, 1917 (9), 27. 
HISSINK, D. J., Bied.Zentr., 1817 (46), 138. 

V. — 50(7 Acidity. 

Cameron, Frank K., 'The Soil Solution, or the Nutrient Medium for Plant 

Growth' (Chemical Publishing Co., Easton, Pa.). 
Baumann, a., and Gully, E., ' Untersuchungen uber die Hiimussauren,' II., Mitt. 

d k bayr. Moorkulturanstalt, 1909, Heft 4. 
Harris, J. E., 'Soil Acidity,' Mich. Tech. Bull. 19, 1914. 
Daikuhara, G., 'Uber saure. Mineralboden,' Bull. Imp. Central Agric. Expt. Sta., 

Tokio. 1914, 2, 1-^0. 
EiCE, Fkank E., 'Studies on Soils: I. Basic Exchange,' J. Physical Chemistry, 

1916, 20, 214-27. 
Ramann, E., Bodenkunde, Berlin (Paul Parey). 
Kappen, H., 'Studien am saurem Mineralboden aus der Nahe von Jena.' Landw. 

Versuchs-Stat., 1916 (88), 13-104. 
RiNDALL, A., 'Ueber die chemische Natur der Humussauren,' Internat. Mitt. f. 

Bodenkunde, 1911, 1, 67-80. 
Oden, Sven, 'Zur KoUoidchemie djr HumusstofFe,' Kolloid ZeitFchr., 1915,14, 

123-30. 
Tacke Br., and Suchting, H., 'Ueber Humussauren,' Landw. Jahrb., 1911, 41, 

717-54. 
Tacke Br., Densch, A., and Arnd, Th., 'Ueber Humussauren,' ibid., 1913, 45, 

195-2H5. 
Truog, E'., ' The Cause and Nature of Soil Acidity, with special regard to Colloids 

and Absorption,' Journ. Fhy.-^. Chem., 1916, 20> 457-84. 
Christensen, H. R., Soil Science, 1917 (4), 115. 
Schollenberger, C. J., Soil Science, 1917 (3), 279. 

VI. — Pan Formation. 
MUNST. Bied. Zentr. Agrik. Chem., 1902, (41), 3-10. 
Ramann, ' Bodenkunde.' 
MORISON. C. T. G., and Sothers, D. B., ' The Solution and Precipitation of Iron in 

the Formation of Iron Pan.' Journ. Agric. Soi., 1914 (g), 84-96. 
Stremme, H., ' Kolloid Zeitsch,' 1917(20)- l^Jl- 

VII. — Flocculation and Befloccidation. 

ROHLAND, P., ' Die Tone,' Vienna, 1910. 
Atterberg, a.. Int. Mitt, fiir Bodenkunde, (1), 10. 

Hardy, W. B., 'A Preliminary Investigation of the Conditions which Determine the 
Stability of Irreversible Hydrosols,' Proc. Roy. Soc. 1899, Ixvi. 110-25. 

(*fl also ' Electrolytes and Colloids, The Physical State of Gluten,' Wood & 
Hardy, ibid., 1909. Ixxxi. 38-4S.) 
Hall, A. D.. and Morison, C. T. G., ' The Flocculation of Turbid Liquids by Salts,' 

Journ. Agric. Sci., 1907. ii., 244-56 
Pickering, S. U., Proc. Roy. Soc, 1918, 94, A, 315-325. 

YIl].— Other Effects. 

Buddin, W.. Journ. Agric. Sci., 1914 (6), 4.52-455. 
Wolkofp, M. T., Soil Science, 1917, (3), 42':^. 

IX. — Colloids and Bacterial Plaiii Life. 

Gola, G., ' Osservazioni sopra i liquid! circolahti nel terrano agrario,' Ann. d. R 

Accad. Agric, Torino, 1911, 54, 37 pp. 
SoHNGEN, N. L., 'Einfiuss von KoUoiden auf microbiologische Prozesse,' Centr. 

Bakt. Par., 1913 (38). 621-47. 
Cavers, Journ. Ecology, 1914 (2), 209. 

X. — Estimation of Soil Colloids. 

Sjoilema. Journ. f. Landw., 1905 (53), 67. 
Endell, Kolloid Zeitsch., 1909 (4), 246. 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 81 

Ashley, H. E., 'The Colloidal Matter of Clay and its Measurement,' U.S. Geol. Sur., 

Bull. 388, 1909. 
Hassler, Landw. Versuchs-Stat., 1911 (75), 377. 
Hanley. J. A.. Journ. Agric. Sci., 1914 (6). 58. 

Tadokoeo, T., Journ. Tohoku Imp. Univ. Sapporo (Japan), 1914, (6), 27. 
MiTSCHERLiCH. (Papers summarised in Internat. Mitt. f. Bodenkunde, 1912 (1), 

463-480.) 

XI. — Const itue/it.i of the Soil. 

Russell, B. J., ' Soil Conditions and Plant Growth,' Longman, 1917. 

XIL— General. 
Eheenbekg, Paul, ' Die Bodenkolloide (Steinkopf),' 2nd edn., 1918. 



SEWAGE rURIFICATIUN WITH REFERENCE TO 
COLLOID CHEMISTRY. 

By Edward Aruern, I).Sc., F.I.C, Chief CheDiist, Rivers 
Department, Manchester Corporation. 

Although the problem of sewage purifii-ation, as it is known 
to-day, dates back to the introduction of the water-carriage 
system in the early part of the nineteenth century, the signifi- 
cance of colloid chemistry in relation thereto has only been 
observed within comparatively recent years. 

Even at the present time, although certain theories have been 
elaborated with respect to the fate of the colloid matter during 
the purification process, in the main such theories have been 
established by analogy from the known characteristics of organic 
colloids and their behaviour under certain conditions rather than 
from any systematic study of the colloid matter actually present 
in sewage. So far as the writer is aware, no reliable data are 
available with respect to the separation, estimation and identifi- 
cation of the actual colloids present originally in the sewage and 
during the various stages of the purification process. 

With the view, therefore, oi' indic-ating the present position in 
regard to the subject it is proposed (a) to state briefly the problem 
and {})) to give a resume of the chief theories advanced with 
respect to the mechanism of the changes involved in the purifica- 
tion process, with special reference to the points of contact with 
colloid chemistry. 

Briefly, ordinary domestic sewage may be said to be the water 
supply polluted by human excremental matter, kitchen and other 
domestic waste products. As in the majority of cases a combined 
drainage system is adopted, road detritus and washings must 
be added. 

The character and strength of domestic sewage varies very 
considerably, dependent on the following factors: — 

(i) The extent to which the water carriage system has been 

adopted, 
(ii) The water consumption per head of population con- 
nected to the sewer, 
(iii) Whether a combined, separate or partially separate 
system is in vogue. 



82 REPORTS ON THE STATE OF SCIENCE. — 1918. 

(iv) Length of travel of outfall sewer. 

(v) Eainfall, contour of district, nature of subsoil, and 
character of sewers, &c. 

In industrial areas the character of the sewage is altered to an 
extent dependent on the nature and relative volume of the trade 
wastes admitted to the sewers. 

In certain districts, e.g., in woollen districts (Bradford, Hud- 
dersfield, &c.), or centres of chemical industry (Manchester, Bir- 
mingham, «&c.), these are such as to alter very materially the 
character of the sewage, and consequently to vary the problem 
of its purification. 

The main constituents of domestic sewage have been sum- 
marised by Fowler as follows : — 

1 . Matters in actual suspension : 

(a) Sedimentary matters, such as silt and sand, &c. 

(6) Floating and finely divided suspended matters 

(paper, rags, faeces, animal and vegetable 

debris, &c.). 

2. Colloidal matters in pseudo solution or emulsion : 

Products of faecal emulsion, soaps and fatty matters, &c. 
(3. Matters in true solution : 

Ammonium salts resulting mainly from the hydrolysis 
of urea. Nitrogenotis substances — urea, products 
of the decomposition of albumen — peptone like 
bodies, carbohydrates; mineral salts^ — chiefly 
sodium chloride, with phosphates mainly derived 
from urine. 

It will be understood that on account of its complex character 
and the unstable nature of its organic contents it is practically 
impossible to differentiate with anything like a high degree of 
accuracy the various states of the organic matter present in 
sewage which under physical and biological action is subject 
to transition from one form to the other. 

(J'vShaughnessy has shown that the colloid matter in pseudo 
solution is derived mainly from the faecal matter present, and 
that although there is a limit to the amount that can be taken up, 
the actual quantity (as measured by the 4 hours' oxygen absorp- 
tion test) varies with the volume and character of 'the diluting 
water, the time of contact and the amount of agitation. 

It is thus evident that the amount of organic " hydrosols " 
varies very considerably in different sewages. For an average 
domestic sewage it may be taken that roughly one-half of the 
soluble organic matter is present in pseudo solution. 

Sewage is siich a heterogeneous mixture of complex and varying 
character that apart from such determinations as chloride con- 
tent, ammonium salts, organic nitrogen, total suspended and 
dissolved (true and pseudo solution) solids, its chemical examina- 
tion is usually confined to certain empirical tests such as 
"albuminoid ammonia" resulting from the distillation of the 
sewage with an alkaline solution of permanganate of potash 
after removal of the ammonium salts, which is taken as a measure 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 83 

of the albuminous bodies present, and "Oxygen absorption" 

N 
from an acid solution of permanganate (usually — K MnO^) 

'80 
under stated conditions, which gives an indication of the amount 
of oxidisable matter present. 

For the purpose of controlling purification plants, in addition 
to the above tests, tlie amount of oxidised nitrogen (Nitrite and 
Nitrate) is deterniined in the effluent. 

Incubation will show whether the effluent is putrescible, and 
determination of the amount of dissolved oxygen absorbed by 
the effluent from aerated water, as recommended by the Royal 
Commission on Sewage Disposal as a Standard Test, will afford 
valuable information with respect to the matter still capable of 
fermentation, and consequently of the extent to which the 
oxidation change has been carried. 

With the object of obtaining information in relation to what 
happens to the colloidal matters during the purification process, 
at any rate so far as the " hydrosols " are concerned, these tests 
have been supplemented by submitting the sewage and effluents 
to dialysis and thus determining the proportion of dialysable to 
non-dialysable matter and their respective oxygen absorption 
and albuminoid ammonia content, see Rivers Committee Report, 
Manchester, 1901, Krohnke & Biltz, Fowler & Ardern, Travis &, 
Johnston, O'Shaughnessy & Kinnersley (1901-1906). 

An objectionable feature of this method of attack is the time 
required by the dialysis operation, which is usually not less than 
24 hours, even where the determination is stopped when equi- 
librium is attained (as measured by the chloride content) on 
either side of the membrane employed, during which period there 
are many possibilities of change of character in an unstable liquid 
like sewage. In the method employed by Johnston for the 
complete separation of the non-dialysable from the dialysable 
constituents of the sewage, a period of 6 days usually elapsed. 
The sewage and effluents were sterilised by the addition of acid 
with the idea of obviating changes due to bacterial action, but 
it is obvious that mere acidification is likely to alter the character 
of the samples under examination. 

The method proposed by Riibner of coagulating the colloidal 
matter by precipitation with acetate of iron surmounts this diffi- 
culty but introduces other errors with respect to the removal of 
organic matters in true solution. Fowler and others elaborated 
this test and called it the " clarification test," while Rolants 
compared the effect of acetate of iron with that of calcium 
chloride and sodium phosphate, alumina, and powdered talc, 
respectively, the latter material being employed with the idea of 
avoiding precipitation of organic matter from crystalloidal 
solution. 

A difficulty common to both these methods of investigation is 
the character of the preliminary treatment of the sample, under- 
taken for the removal of the finely divided non-colloidal matter. 
Tlie method of procedure is either to allow tlie sjimple to stand 



84 REPORTS ON THE STATE OF SCIENCE. — 1918. 

for a stated period and to work with the supernatant liquid, or 
to filter the original sample through filter paper. The first 
procedure is open to the objection that matters in what may be 
termed ' macroscopical ' suspension are incompletely removed, 
while filtration through paper, in addition to the removal of 
such matter, may also remove actual colloids by the absorptive 
action of the film of suspended matters formed on the filter paper. 
It will thus be seen that it is difficult to differentiate between 
particulate suspended matter in a state of fine division and actual 
colloidal matter. 

The object of sewage purification is primarily to obtain an 
effluent which will not pollute the water course into whicli it is 
discharged. 

An effluent may be said to be entirely satisfactory which avoids 
the following: — 

1. Secondary decomposition which may give rise to aerial 

nuisance. 

2. Deaeration of the body of water into which it is 

discharged. 

3. Deposition on the bed of the watercourse. 

Having regard to the conditions usual in this country of the 
relative volumes of the stream and sewage, the production of such 
an effluent involves the removal of suspended matters and of the 
putrescible organic matter in colloidal and crystalloidal solution. 

In the following paragraphs. is given a brief account of the 
methods generally adopted to eft'ect this object. 

The sewage as it arrives at the outfall works is usually passed 
through a detritus and screening chamber, where the heavier 
sedimentary matters, road detritus, &c., are removed, together 
with floating matters, such as rags, paper, &c., and a proportion 
of the non-disintegrated faecal matter. 

Apai-t from the treatment of sewage on land by broad irriga- 
tion, or in some cases of intermittent filtration, or by the activated 
sludge process, which will be briefly considered later, the screened 
sewage then receives preliminary treatment by one of the 
following alternate methods: — 

1. Plain sedimentation tanks. 

2. Chemical precipitation tanks. 

'A. Specially designed tanks such as the Hampton (Hydro- 
lytic) or Emscher tank. 

4. Specially constructed contact beds, such as the Dibdin 

slate filter. 

The main object of this preliminary treatment is to remove, as 
far as possible, the actual suspended matters in order to facilitate 
the subsequent filtration of the sewage. 

In septic tank treatment, anaerobic fermentation of the sewage 
is encouraged, with the view of reducing the volume of sludge 
to be dealt with, while the double-decked tanks of Travis 
(Hampton) and Imhoft' (Emscher) are designed to confine such 
anaerobic action to the deposited sludge and so avoid a septic 
effluent. 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 85 

Except in special cases where the sewage itself contains trade 
waste which may coagulate colloidal matter, simple sedimentation 
of the sewage, while doubtless effecting removal of a cousidenible 
proportion of the organic colloidal matter in the ' gel ' form, 
is practically without effect on that in the ' hydrosol ' condition. 

A certain proportion of the ' hydrosols ' will be carried down 
by chemical treatment, but unless a fairly heavy dose of salts 
O'f iron or alumina with or without lime is employed, when the 
process becomes exijensive and in many cases impracticable, the 
tank effluent still contains appreciable quantities of organic 
colloidal matter. 

Krohnke and Biltz, Eolants and others liave shown that in 
the main the sewage colloids possess a negative charge which 
very probably is not without effect in regard to the value of the 
salts of trivalent metals of opposite charge, such as those of iron 
and alumina, in coagulating the colloidal matter present in 
sewag'e. Purely chemical reactions and the eff'ect of the extended 
surface afforded by the precipitate formed, cannot, however, be 
neglected in considering the process of chemical precipitation. 

While considering this question, mention should be made of 
the suggestion of Eohlands to use plastic clay as a means of 
separation of colloid matter. Polz, however, reports that as the 
result of large scale trials with dyeworks effluent, the process is 
both unsatisfactory and impracticable. 

Reference should also be made to Degener, who, arguing by 
analogy from the absorptive action of the ' humus ' in soil, 
w^orked out a method of purifying sewage by precipitation with 
powdered lignite and iron salts, which it is claimed is capable of 
removing not only the suspended solids, but also the colloid and 
other putrescible matters in the sewage to the extent of producing 
9, non-putrescible effluent. Dunbar, however, reports that it is 
only applicable in certain special cases, and that its cost is too 
great for general adoption. 

Effluents from ordinary septic tanks usually contain appre- 
ciably more finely divided suspended matter than the effliient 
resulting from either chemical treatment or simple sedimentation, 
as the result of the constant rising and falling of particles of 
sludge due to the gas evolved consequent on the anaerobic 
decomposition of the deposited sludge. 

It has been found generally that as a r.esult ol septic treatment 
there is a small though appreciable reduction in the amount of 
oxidisable matter in true solution. 

With regard to the action on the matter in pseudo solution, 
this seems to vary with the character of the sewage treated with 
particular reference to its original colloid content. 

O'Shaughnessy, working with a mixed trade sewage of low 
colloidal content, concluded there was a slight increase in the 
oxidisable matter in pseudo solution as the result of treatment in 
septic tanks, and Fowler and others have stated that where septic 
action was vigorous as the result of higher temperature there is 
evidence of some slight increase. 



86 REPORTS ON THE STATE OF SCIENCE. — 1918. 

On the other hand Rolants, employing a precipitation method 
for removal of colloids, found that while the percentage of the 
total oxidisable matter present in pseudo solution was slightly 
higher in septic tank effluent than in the sewage treated, the 
actual amount of colloidal matter (as measured by the perman- 
ganate test) was, if anything, rather less. On determining the 
organic nitrogen and organic carbon contained in the colloids 
present, which was considered to give a better appreciation of the 
colloid matter than does the oxygen absorption test, he found in 
every case a diminution of colloid matter in the septic tank 
effluent as compared with the original sewage. 

On the whole, it may be considered that septic action as 
exhibited diu'ing septic tank treatment has no material effect on 
the amount of matter in pseudo solution, the differences found 
being veiy little more, if any, than the errors in the method of 
estimation. 

The chief object of preliminary treatment in slate beds is to 
keep the solids deposited therein under aerobic conditions as far 
as possible, and Dibdin has shown that if operated in a proper 
manner a considerable destruction of the deposited sludge is 
brought about by the agency of bacteria, moulds, and higher 
organisms such as protozoa, worms, &c. 

While it is possible that contact with the slates will tend to 
flocculate, by surface action, some of the matter in pseudo solu- 
tion, the filters are too open to be very effective in this respect, 
and it is understood that the effluents obtained are still turbid 
and contain appreciable quantities of colloidal matters. 

It can be stated that with properly designed plant, having 
regard to the maximum permissible velocity of flow, a more or 
less complete removal of the grosser suspended solids can be 
obtained, and that, dependent on the character of the sewage, a 
considerable proportion of the more finely divided solids, includ- 
ing, doubtless, colloids in the ' gel ' condition, may be effected. 

It is, however, evident that none of these preliminary processes, 
except heavy chemical treatment, affect appreciably the organic 
matter in pseudo solution. 

The resultant effluent, therefore, contains practically the 
original sewage solids in solution together with a varying propor- 
tion of the finely divided suspended solids, and its subsequent 
purification involves the application of extended surfaces. 

This is usually effected by distribution on land or on artificial 
filters composed of various inert media of different grades, in 
which the liquid is held in contact with the filtering media 
(placed in water-tight tanks), or is allowed to percolate through, 
either intermittently or continuously. 

Briefly, it may be said by the adoption of any of these methods 
no difficulty need be experienced in obtaining a satisfactory 
effluent, provided due attention is paid to the design of the puri- 
fication works and to its capacity in relation to the volume and 
character of sewage treated. 

With the object of dealing with the mechanism of the complex 
changes, physical, chemical and biological, which take place 



ON COLLOID CHESIISTRY AND ITS INDT7STRIAI, APPLICATIONS. 87 

during the oxidation or purification process, it is proposed to 
consider briefly the three main theories which have been advanced 
in explanation of the purification phenomena, more particularly 
with reference to the fate of the colloid matter. 

The earliest theory advanced with respect to the mechanism 
of the purification changes effected by the filtration of ' sewoge ' 
was based on the work carried oait at the Lawrence Experimental 
Station, Mass., in respect of the development of the intermittent 
sand filters as advocated by Frankland, as a practical means of 
sewage purification. 

According to this theory, the suspended solids applied with 
the sewage or tank efiluent are arrested mechanically in the 
filter by virtue of its fine pores, and subsequently oxidised, and 
the organic matter in solution is directly oxidised and mineralised 
by bacterial agency during the course of its passage through the 
filter with the accumulation within the filter of small quantities 
of 'humus,' which is veiy resistant to further fermentation. 
Presumably colloids are included in the organic matters in solu- 
tion, although they are not referred to specifically. 

This simple representation of the purification process received 
almost universal support, notably by Stoddart as recently as 1909. 

Dunbar assumed that it was not possible to bring about the 
complete oxidation of the complex organic matter present in 
solution in sewage during the short period of time taken by the 
liquid in passing through the filter, and as the result of a series 
of experiments extending over a co^nsiderable period (1897-1900) 
carried out bv him and his colleagues at the Hamburg Hygienic 
Institute {vicle ' Principles of Sewage Treatment ') he advanced 
what is known as the "absorption theory" of sewage purifi- 
cation. 

This theory explains the mechanism of the purification changes 
as follows : — 

1. The actual suspended matters are removed by attraction 

of the filtering media, &c. 

2. The dissolved matters (true and pseudo solution) are 

retained by absorption phenomena, which is 
accelerated and increased as the slimy matter, or what 
is termed the bacterial film, accumulates on the media 
as the filter becomes mature. 

3. That the matters thus retained are oxidised by chemical 

action (condensed oxygen, &c.), and by the agency of 
bacteria and higher' forms of life. The resultant 
soluble products — mineral salts, amino-acids, «S:c. — are 
subsequently washed out of the filter by succeeding 
quantities of sewage treated. 

4. That this absoi-ption process is prevented from ceasing 

by the action of micro-organisms, &c., in the presence 
of atmospheric oxygen. 

5. There is a residue of organic matter, &c., wliich is very 

resistant to further oxidation changes, wliich either 
accumulates in the filter or is discharged with the 
effluent. 



88 EEPOETS ON THE STATE OF SCIENCE. 1918. 

It will be noted that this theory draws no distinction between 
matters in true and pseudo solution so far as the mechanism of 
the purification changes is concerned. 

Experience with the operation of the Hampton sewage works, 
where relatively large quantities of sludge accumulated in the 
filtration area, led Travis to study the question of sewage colloids 
in relation to sludge production. As the result of a series of 
experiments eari'ied out in conjunction with Johnston, he 
advanced in 1905 what is known as the Hampton Doctrine. 

According to this theory the purification process is primarily 
and essentially a de-solution effect brought about purely by 
physical causes and that any bacterial or biological action is 
definitely ancillary. 

Unlike Dunbar's theory, a distinction is drawn with regard to 
the mechanism of the purification process as between organic 
matter in colloidal solution and matter in true solution. 

It is held that whereas ' organic matters and products in actual 
solution, e.g., ammonia, sulphuretted hydrogen and volatile 
products, are absorbed by the accumulated deposits in the filter,' 
the solids in colloid solution are coagulated or precipitated ' in 
virtue of a physical action ' — effect of extended surface contact, 
&e. 

These coagulated colloids are either retained in the filter or 
discharged with the effluent from the filter, and any biolytic 
action on them is a verv slow and prolonged process, and conse- 
quently in addition to the actual suspended solids in the sewage 
or tank-effluent treated, the amount of such coagulated colloids 
which have been termed ' ultra sludge,' must receive attention 
in considering the amount of the total sludge to be dealt with. 

In discussing these theories, it is proposed to- confine attention 
as far as possible to the purification effect on matters in colloidal 
solution. 

Briefly, it may be said that — 

(i) In the earlier theory, especially as propounded by Stod- 
dart, that such matters are held to be oxidised directly 
by bacterial agency during the passage of the liquid 
through the filter, 
(ii) That Dunbar's theory provides for their preliminary 
absorption by the filtering media and the gelatinous 
coating thereon, with subsequent more or less rapid 
oxidation by agency of condensed oxygen, bacteria 
and higher forms of life, 
(iii) That according to the Hampton Doctrine, such absorp- 
tive processes are confined to the matters in true solu- 
tion, and that the matter in pseudo solution is 
coagulated by virtue of a physical action. That the 
subsequent biolytic oxidation of the matter thus 
deposited is a very prolonged process. 

In connection with the question of absorption, it may be 
mentioned that Clark, and later Clifford, have demonstrated that 
the mean time of passage of sewage through a filter as operated 
in practice, while it varies considerably, dependent on several 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 89 

factors, is, on the wliole, niucli longer than the few minutes 
spoken of by Dunbar, and may in some cases amount to more than 
one hour, wJiich would allow time for oppreciable bacterial action. 

Also that Harriette Chick, Fowler and Gaunt, and Stoddart have 
shown that absorption of ammonium salts does not take place under 
sterile conditions except with material such as clinker, &c., which 
allows of chemical interaction between the liquid and the media. 
Stoddart has extended this observation to solutions of albumen and 
was unable to confirm Dunbar's experiment which shewed 50 per 
cent, loss of albumen. He suggests either preliminary decomposition 
(prior to use) with formation of ammonia which would be partially 
fixed by the clinker, or direct chemical interaction as a possible 
explanation. It is obvious that experiments designed to shew purely 
absorptive phenomena should be carried out with material entirely 
inert, such as pure quartz as used by Fowler and Gaunt. 

Stoddart 's conclusion that there is no evidence of the preliminary 
absorption of the soluble constituents of sewage was based on the 
results of his experiments on the nitrification of solutions of (a) 
ammonium salts (b) urea (c) albumen and (d) of sewage deprived of 
its suspended matter by filtration through paper, in which the flow 
through his experimental filter (seeded with a vigorous growth of 
nitrifying organisms) was interrupted from time to time, and the 
liquid treated replaced by salt solution of known strength applied at 
exactly the same rate. 

The coincidence of a series of curves plotted with respect to the 
time taken to attain maximum nitrification and maximum chloride 
content was claimed to establish that preliminary absorption did not 
take place. 

Stoddart also objects to the absorption theory, developed as it w-as 
as the result of studies with contact beds, being applied to the modern 
percolating filters where the conditions diif er very considerably. On 
the other hand, Dunbar considers that such altered conditions are 
more favourable to absorptive phenomena. 

For a full discussion of the difference between the theory of 
preliminary absorption of colloidal matter and of its direct coagulation 
and deposition in the filter, the reader is referred to a paper presented 
by Travis to the meeting of the Association of Managers of Sewage 
Disposal Works at Leicester, (July 4th, 1908), which appeared in the 
July 10th, 1908, issue of the Sicrveyor, and to the discussion thereon 
which ensued between the author and Liibbert, of the Hamburg 
Hygienic Institute. 

So far as the mechanism of the preliminary removal of the matter 
in colloidal solutions is concerned, both Dunbar and Travis agree 
that it is essentially the result of physical action ; mention should 
therefore be made of the work of Fowler and Mumford. They found 
that under strictly aerobic conditions, a bacterium isolated from 
a body of water receiving colliery discharges, acting through its 
enzyme in the presence of small quantities of iron salts, was capable 
of coagulating sewage colloids in the course of a few hours. Such 
removal of colloid matter from pseudo-solution is effected without 
the aid of surface content other than is provided by the air bubbles 
and the matter precipitated. 



&0 REPORTS ON THE STATE OF SCIENCE. 1918. 

The evidence available witti respect to the mechanism of the 
removal f i om sewage of organic matter in pseudo-solution may be 
summarised thus : — 

(i) The experiments of Stoddart designed to show its direct 
oxidation by bacterial agency cannot be considered 
conclusive. On the other hand it has not been demon- 
strated that under the favourable conditions present in an 
efficient filter, in which the sewage passes in thin films 
over a network of media covered with an active bacterial 
slime, the mean time of passage is insufficient to allow of 
direct biolytical oxidation of some portions of the organic 
matter in pseudo-solution. 
(ii) While it is accepted that sewage colloids may be precipitated 
or coagulated by intimate surface contact, this 'de-solution' 
theory can scarcely represent the whole phenomena of 
colloid removal otherwise such action would continue 
in the absence of micro-organisms. 
(iii) The conditions met Avith in a mature and efficient filter are 
such as to render it most probable that absorption phe- 
nomena play an imjDortant part in the removal of matters 
from pseudo-solution. 

In considering the final fate of the matters removed from pseudo- 
solution during the purification process it may be said that, inde- 
pendent of what may occur with experimental filters inoculated with 
vigorous growths of micro-organisms, and operated under ideal 
conditions, Stoddart's view that none of the solid matter retained in 
sewage filters is derived from organic matters originally in pseudo- 
solution is not consistent with what obtains in actual practice. 

On the other hand the contention of Travis that the retained 
colloids undergo very little change as the result of biolytic action 
was formulated on entirely inconclusive evidence. 

In this connection mention may be made of Dunbar's experiment 
in which a solution of albumen containing nitrogen equivalent to 
the organic nitrogen content of an average sewage was applied to a 
mature filter, with the result that almost quantitative oxidation of 
the sulphur was obtained, while 58 per cent, of the total nitrogen 
appeared in the filtrate, 10 per cent, as ammonia, 20 per cent, as 
nitrate and 25 per cent, as organic nitrogen. Thus 42 per cent, of 
the nitrogen disappeared either in the gaseous form or accumulated 
in the ' humus.' A considerable part of the carbon of the albumen 
also disappeared as gaseous carbonic acid, but a part also went to 
form th^ ' humus ' which accumulated in the filters. 

The Massachusetts intermittent sand filters have demonstrated that 
the amount of retained nitrogenous matter after 18 years' continuous 
operation with 'regulation station' sewage containing its original 
suspended solids "only amounts to from 4 to 5 per cent, of the total 
nitrogen in the sewage applied. Travis estimates this to be equal to 
about 20 per cent, of the original organic nitrogen. 

Recently, Clark in reporting on these filters after they had been 
at work for 28 years, states that for some years only as much sewage 
has been applied as can be purified without increasing the amount of 
organic matter stored in the filters. 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 91 

Comparison of the conditions obtaining in these filters with those 
of the modern ' artificial ' filters in which sewage is treated at very 
much higher rates, leads to the conclusion that the results obtained 
may certainly be considered a maximum effect with respect to the 
resolution of the organic matter deposited in the filter, at any rate so 
far as any practicable scheme of sewage filtration is concerned. 

The fact that the sewage treated contained its original solids 
in suspension unfortunately precludes any definite conclusion with 
regard to the actual resolution of the solids derived from matters in 
pseudo solution. 

In the Second Annual Report of the State Department of Health 
of Massachusetts (1916), Clark reports the results obtained with the 
operation of a series of sand filters receiving respectively, (a) un- 
treated sewage, (6) settled sewage, (c) sewage after treatment in 
straining filter, and (d) sewage clarified by precipitation with 
sulphate of alumina The volume of sewage applied to each filter 
was varied so that each received as nearly as possible equal amounts 
of organic matter (measured by the organic nitrogen). It is interest- 
ing to observe that working in this manner there was no material 
difference in the amount of nitrogenous matter stored in the respective 
filters, measured by determining the amount of albuminoid ammonia 
in the sand. 

It would thus appear that the nitrogenous organic constituents of 
sewage whether in actual suspension or in colloidal solution are more 
or less equally amenable to biolytic action, and consequently the 
percentage resolution of total organic matter observed in connection 
with the sand filters treating crude sewage should apply fairly well 
to the matters coagulated from pseudo solution. 

In conclusion it is evident that the total unresolved organic matter 
either retained in the filter or discharged with the effluent, will 
depend on the character (suspended solids and colloid contents) of 
the sewage treated and the rate of application with respect to the 
capacity of the filter, which will vary according to the type em- 
ployed. 

A survey of the subject would not be complete without reference 
to the large scale operations developed by O'Shaughnessy with 
reference to the subsequent treatment of the sludge removed from 
the Birmingham sewage by treatment in sedimentation on septic 
tanks. 

This sludge is submitted to prolonged anaerobic fermentation, 
whereby appreciable auto-digesiion of the sludge occurs with loss of 
colloidal character. By this treatment a dense and granular material 
is produced without nuisance. (Vide Reference, 1914, J.S.C.I., 
No. 1, vol. xxxiii.) 

The following reference to the "Activated Sludge" process of 
sewage purification is made on account of the rapid removal of 
oxidisable matter in pseudo-solution, which is effected without the 
aid of actual surfaces, other than is provided by the particles of 

sludge. 

An " active " sludge is built up as the result of the oxidation by 
aeration of successive quantities of screened and detritus free 
sewage. 



92 REPORTS ON THE STATE OF SCIENCE. 1918. 

This sludge is flocculent in character, has a very high bacterial 
content and contains numerous higher forms of life especially 
ciliated protozoa. 

When sewage is aerated in intimate contact with from 20 to 25 
per cent, (by volume) of activated sludge there is a rapid initial 
removal of oxidisable matter from pseudo-solution, with the produc- 
tion of a well clarified effluent, which is nitrified on further aeration. 

Judging by the volume of sludge produced it is presumed that 
the colloidal matters are removed from solution either by the 
absorptive action of the flocculent sludge or coagulated by intimate 
contact with the sludge particles, or as the result of enzymic action. 

While Bartow has shown that large quantities of carbonic acid 
are produced during the purification process, which is indicative of 
vigorous biolytic action, the high proportion of organic matter in the 
resultant sludge appears to preclude any material destruction or 
resolution of the organic matter present in the original sewage either 
in actual suspension or in colloidal solution although ii is evident 
from its appearance there has been a considerable alteration in its 
physical character. 

The high nitrogen content of activated sludge, which varies from 
4 to 7 per cent, (dry matter) dependent on the character of the 
sewage treated, leads to the same conclusion, as Clark has shown 
that the sewage colloids contain much more nitrogen than do the 
grosser suspended solids. 

There is however an undetermined factor, viz. : — to what extent, 
if any, is there any fixation of atmospheric nitrogen ? 

Ardern and Lockett have studied this question but further infor- 
mation is required before any definite pronouncement can be made. 

As previously stated, the sludge is quite flocculent and readily 
separates out from the purified sewage. 

Presumably on account of its gelatinous condition, the water 
content of the sludge is very high and cannot be reduced below 
95 per cent, by simple sedimentation. 

When this percentage has been reduced to from 88 to 90 per cent., 
either by centrifuge, or by treatment on drainage filters, the sludge 
is of the consistency of a fairly stiff jelly, whereas ordinary sludge 
obtained from the sedimentation of sewage, containing a similar 
amount of water, is quite fluid and can be readily carried and 
discharged through pipes. 

The solution of the problem of the best means of pre'iminary 
de-watering of this sludge, prior to drying, involves a study of the 
conditions favourable to the removal of water retained by colloids in 
the " gel " state. 

Chalkley Hatton has shown that such de- watering can be effected 
by treatment in a modified type of filter press, with the production 
of a cake containing 75 to 80 per cent, moisture. 

There is, however, room for research, with special reference to 
electrical effects, in regard to the most economical method of 
de-waterising and drying the sludge. 

The problem is one of considerable importance to agriculture, 
involving as it does the utilisation of the full value of the sludge as 
a fertiliser, 



ON COLLOID CllEMISTKY AND ITS INUUSXKIAJ. APPLICATIONS. 93 

A. complete bibliography of the activated sludge process will 
be found in Porter's publication, given in the list of references 
submitted. 

BiBLIOURAPHY. 

1901. 
' 33rd Annual Keport of State Board of Health,' Mass., p. 272-5. 

Examination and analysis of original sediment and suspended .solids discharged 
from percolating filter. 
'Annual Eeport Eivers Department,' March 1901, pp. 40-41. 

Determination of colloidal iron in open septic tank effluent. Suggested dialysis 
as a means of studying colloids in sewage and effluents. 

1903. 
Kattein k LuBBERT, ' Gesund. Mag.', No. 25. 

Absorption phenomena occurring in sewage filter beds. 

1904. 

BiLTZ U. Krohnke, ' Hyg. Kunds.', 1 Mai, 1904. 

' Ueber organische KoUoide aus Stadischen Abwasser und deren Zustandsaffinitat.' 

Considerable proportion of the oxidisable matter in sewage, after filtration paper, 
is incapable of passing through a parchment membrane. State sewage colloids have 
a negative charge and are precipitated by iron and zirconium salts. 
' 36th Annual Report of State Board of Health,' Mass. 

Time of passage of sewage through percolating filter determined. 

Results of 15 to 18 years continuous operation of sand filters, only 4 or 5 per cent 
of total nitrogen applied to filter was retained in the sand. That this material is 
very resistant to bacterial action. 

1905. 

Fowler & Ardern, ' J.S.C.I,' No. 9, vol. xxiv. 

' Suspended Matters in Sewage and Effluents.' 

Dialysis of sewage showed appreciable quantities of oxidisable matter in pseudo- 
solution — proportion of whole varies considerablj' with different sewages. Suggest 
method as a means of gaining additional information with respect to purification 
process. 
GrAGE DE, M., ' Jour. Amer. C.S.', vol. xxvii., No. 4. 

' Contribution to the Bio Chemistry of Sewage Purification. The Bacteriolysis 
of Peptones and Nitrates.' 

Studies carried out at the Lawrence Experimental Station, Mass.; under the 
direction of H. W. Clark. 
Chick, Harriette, 'Proc. Roy. Soc,' B., vol. Ixxvii. 

'A Study of the Process of Nitrification with Reference to the Purification of 
Sewage.' 

1906. 

O'SHAUGHNKSSY & KiNNERSLEY, J.S.C.I. No. 15, VOl. XXV. 

' The Behaviour of Colloids in Sewage.' 

Extension of preliminary investigation by Fowler and Ardern, aud determination 
of source of colloidal matter. 
Jones & Travis, ' Proc. Ins. C. E.', vol. clxiv., pi. 2. 

' The elimination of suspended solids and colloidal matter from sewage.' 
De-solution theory of sewage purification developed as the result of experience 
with the working scale plant (Hampton Sewage Works) ; and a series of experiments 
with regard to the possibilities of physical action on sewage colloids. 
Johnston, J. H., ' J. Roy. San. Ins.', vol. xxvii., No. 10. 
" The Organic Colloids of Sewage." 

.Description of Hampton experiments with regard to de-solution theory, 
LXJBBERT, ' Gesund. Ing.', 1906. 

' On the nature of the action of oxidation filters.' 
State Board of Health, Mass. ' Annual Report,' p, 283. 



94 EEPOETS ON THE STATE OF SCIENCE. 1918. 

1907. 
DiBDiN, 'Analyst,' April, 1907. 

The disposition and analysis of sewage debris in contact bed.' 

Concludes that there is a considerable destruction by biological agency of the 
matters deposited in slate beds at Devizes. 
BiLTZ & Keohnkb, 'Z. angew. Chem,' 1907. 20, 883-887, 

A Description of Colloid Matter from Sewage. 

Partial separation of oxidiaable matter obtained by the dialysis of sewage by 
treatment with various solvents — Benzene, carbon-bi-sulphide, nitro-benzene and 
petroleum. 
Clark, H. W., ' Eng. New,' .57, 607. 

Comparative disposition of organic matter by sand, contact and sprinkling filter. 
Clifford, W., ' J.S.C.I.', vol. xxvi.. 739. 

' The time of passage of liquid through percolating beds.' 

Employed a modification of the St. Lawrence Experimental Station, Mass., where 
salt solutions were used. 
Edbner, M., 'Archiv. fur Hygiene,' 14, 

' Das Stadtische Sielwasser und seine Beziehung zur Flussverunreinigung.' 
; Eecommends separation of colloids in sewage (after settlement or filtration 
through paper) by boiling with solutions of iron alum and acetate of soda. 
Fowler & Gaunt, 'J.S.C.I.', No. 13, vol. xxvi. 

' The interaction of dilute solutions of ammonium salts and various filtering media.' 
EOHLANDS, P., ' Z. Chem. und Ind. Kolloide,' 1907, 2, Abst. ' J.S.C.I.', vol. xxvii. 
p. 34. 

' Clay as a semi permeable and its use for purifying factory effluents, and sewage.' 

Shows absorptive properties of plastic clays. 
Feeundlich, ' Z. angew. Chem.', 20, 749-50. Abst. ' J.S.C.I.', vol. xxvi., 646. 

' Colloid precipitation and absorption.' General discussion of the properties of 
colloidal ' sols.' 
DziERZOWSKY, 'Gesund. Mag.' 1907, 

' Zur Theorie Kunstlicher Biologische Filter.' 

Absorption phenomena. 
Dunbar, Hamb., 1907, trans, by Calvert — Griflin & Co., Ltd , Strand. 'Principles 
of Sewage Treatment,' 1908. 

Text book on the subject. Gives comprehensive references, especially to his own 
and his colleague's work, in connection with the development of the absorption 
theory. 

1908. 

Clifford, W., ' Proc. Ins. C. E.', vol. clxxi., part ii. 
' On Percolating Beds.' 

A continuation of a previous study, see 'J.S.C.I.', vol. xxvi., 739. 
Fowler, Evans & Oddie, ' J.S.C.I,', vol. xxvii. No. 5. 

' Some applications of the ' Clarification Test ' to sewage and effluents.' 
Rubner's test of precipitation of colloidal matters in sewage by means of acetate of 
iron, examined and compared with results obtained from dialysis. Recommend 
use in control of sewage purification plant. 
Travis, Owen, ' The Surveyor,' vol. xxxiv., 63-66. 

vol. xxxiv., 625-7, 604-6. 
and vol. xxxv., 7-10. 
LtJBBEET, A., ' The Surveyor,' vol. xxxiv., 575-8, 598-600. 
(1909), vol. xxxvL, 109-111. 
' The Hampton Doctrine in relation to Sewage Purification.' 

Prolonged discussion between Travis and Liibbert as to respective merits of 
Travis's ' De-solution ' theory and Dunbar's ' Absorption ' theory. Liibbert's commu- 
nication translated by Calvert. 

1909. 

ROLANTS, ' 7th Int. Cong. App. Chem.', London, 1909. 

Section /iiia., 161-f69, Partridge & Cooper, London, E.G., 1910. 

' Les Matieres organique coUoidales dans les eaux d'egout.' 

Examination and modification of Fowlers ' Clarification Test," and estimation 
of colloidal matters in sewage, septic tank effluent and filtrates from contact beds. 
J0HNS0^, J. H., reference as previous p. 171-177. 

' Physical and Biolytic factors in Purification of Sewage.' 

(Concludes from experiments given that physical factor is very great, and that 
the biolytic operation is a very lengthy one. 



ON COLLOIB CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 95 

Stoddart, F. W., reference as previous p. 183-210. 

' Nitrification and the Absorption Theory.' 

Gives the result of a series of experiments in connection with the nitrification 
of ammonium salts, albumen, and sewage, which, it is concluded, disprove ' the 
absorption theory ' of Dunbar. 

1913. 
MuMFOED, B. M., 'Trans. Chem. Soc, 1913, vol. 103. 

' A new Iron Bacterium.' 

Isolated organism from basin receiving colliery pump water. Under aerobic 
conditions is capable of completely precipitating iron from solutions of either 
ferrous or ferric salts. 
FoWLKR & MuMFOED, ' Roy. San. Ins.', vol. xxxiv.. No. 10. 

' Preliminary Note on the Bacterial Clarification of Sewage.' 

Organic matter in colloidal solution in sewage coagulated by inoculation with 
the organism isolated by Mumford, and aeration in the presence of small quantities 
of iron salts. 
ROHLANDS, ' Z. Chem.Ind. Kolloide,'1913,12,4.5-6. Abst. 'J.S.C.I.', vol.xxxii., p. 209. 

' Colour method of determining colloids in effluents.' 

Colloids determined by absorption of aniline blue. 
POLZ, ' Farben-Zeit,' 1913, 24, Sg-^i-e. Abst. 'J.S.C.I.', vol. xxxii., p. 910. 

' Purification of Dye Works Effluents Jay means of Colloidal Clay.' 

States that large scale trial demonstrates method suggeuted by Rohland (Abst 
I J.S.C.I.', vol. xxvii., p. 34) unsatisfactory and impracticable. 

1914. 
O'Shauqhnkssy, 'J.S.C.I.'. No. 1, vol. xxxiii. 

' The Utilisation of the Phenomena of Putrefaction with special reference to the 
Treatment and Disposal of Sewage Sludge.' 
FowiEE & Cliffoed, ' J.S.C.I.', vol. xxxiii., p. 815. 

' Notes on the composition of Sundry Residual Products from Sewage.' 

Includes examination of sludge recovered from various sections of purification 
plant, with special reference to their carbon and nitrogen content. 
O'Shaughnessy, ' J. Inst. San. Eng.', part 2, vol. xviii. 

' The significance of Colloidal matter in the problems of Sewage Disposal.' 

General consideration of question with special reference to the operation of the 
Birmingham sewage purification plant. 
SOHNGEN, 'Ch5m. Wienblad.,' 1914, 11, 42-59. Abst. ' J.S.C.I.,' vol. xxxiii., p. 329. 

'Influence of Colloids on Micro-biological Processes.' 

Presence of certain colloids assists various procerses, e.g., fixation of nitrogen by 
Azobacter and decomposition of starch by Bac. Ochraceus. 

Maec and Sac, ' Koll. Chem. Beihefte,' 1914, 5, 375-410. Abst. ' J.S.C.I.,' vol. xxxiii., 
p. 564. 

' Determination of Colloids in Effluents.' 

Colloids determined by mixing 10 grams of insoi -substance, preferably pure 
BaSo4, with 20 grams of effluent, and shaking for half hour. Original and clear 
solution obtained after separation of insoluble matter, compared by means of the 
interferometer {see 'J.S.C.I.,' vol. xsxi., p. 539). The decrease in refraction is 
proportional to the quantity of colloids in effluent. 

1916. 
Ledebee. 'Chem. News,' 1916, 113, 308-9. 

' Relative Stabilities in Polluted Effluents carrying Colloids.' 
'2nd Annual Report of the State Board of Health of Massachusetts,' 1916. 
P. 128, 'Cause of the Increase of Organic Nitrogen in Activated Sludge.' 
P. 146-7, 'Intermittent Sand Filters operated with Untreatad Sewage.' 
P. 149-50, Intermittent Sand Filters operated with Clarified Sewage.' 

1917. 
PoETEE, J. E., General Filtration Company, Inc. Rochester, N.Y. 

'The Activated Sludge Process of Sewage Treatment.' 

A most complete bibliography of the subject from initial publications, 1914, to 
May 1917. 
Ardern, E., 'J.S.C.I.', No. 14, vol. xxxvi. 

' A resume of the present position of the Activated Sludge proceea of Sewage 
purification.' 



96 REPORTS ON THE STATE OF SCIENCE. 1918. 

COLLOID PROBLEMS IN DAIRY CHEMISTRY. 

{Milk, Butter, Cheese, Margarine, and Ice-cream.) 

By William Clayton, M.Sc, Chief Chemist, Calders Margarine 

Co., Liverpool. 

In this paper it is proposed to treat of Dairy Chemistry under 
special headings, drawing particular attention to the colloid phe- 
nomena and problems involved. Milk (the basis of all the other 
products), butter, cheese, margarine, and ice-cream, each receive 
special consideration : — 

Milk. 

Milk contains substances which are inherently colloidal in nature, 
e.g., casein and albumen, and also materials which behave as colloidal 
systems by virtue of their fine Mate of subdivision, e.g., the fat 
present as emulsion, the cell-content of milk, and the enzymes of 
milk. 

The casein of milk, a protein combined with phosphates of the 
alkaline earths, is present to the extent of about 3 per cent., whilst 
the second protein body, albumin, is present to about 0*5 per cent. 
Casein is so important from the. standpoint of the colloid chemistry 
of milk, that a separate section of the paper has been devoted to it. 
The albumin, known as lact-albumin, is separated from casein, by 
precipitating the latter with acetic acid. Pure lact-albumin is an 
amorphous, tasteless powder. In aqueous solution it is coagulated 
by heating to 70° C, but only about 85 per cent, to 90 per cent, is thus 
precipitated. \_See Rupps. U.S. Dcpt. Agri. Bureau of Animal, Ind. 
Bull. 166. Pp. 1-15. (April, 1913).] Lact-albumin is soluble in 
saturated aqueous Mg SO4, but is precipitated if acetic acid be added. 
A crystalline form of this albumin is obtained if the saturated Mg 
SO4 solution has an equal volume of water added, a little acetic acid 
being present, and then allowed to stand. 

Amongst other reactions given by the albumin proteins, " lact- 
albumin is thrown out of solution by saturation with ammonium 
sulphate, or by addition of tannin, or phosphotungstic acid. It is 
insoluble in alcohol. 

Some evidence has been obtained for the existence in milk of a 
third protein, lacto-globulin, present to the extent of about 0*15 per 
cent. It is soluble in acidified NaCl solutions, is coagulated at 72°C., 
is not coagulated by rennet, and is precipitated by sodium sulphate, 
and tannin. 

(■ Hammarsten, Z. f. physiol. Chemie, 8, 467 (1183-1)- 
See\ Sebelien, Z. f. phi/xiol. Chemie, Q, 445 (1885). 

I Schlossmann, Z. f. p/iysiol. Chemie, 22> 197 (1896). 

The colloid chemistry of milk chiefly centres round the phe- 
nomenon of " protection," in this case, the protective action exerted 
by lact-albumin on casein. The subject has been well investigated, 
and is fairly involved ; for its complete understanding, the com- 
positions of various milks must be studied. The following table of 



OS COr.LOin CHEMTSTRY and its IXDUSTUTAF, ArPMCATIONS. 97 

the average composition of various milks is Leuch's compilation from 
Koenig's, "Chemie der mensch-Nahrung unci Genussmittel." 

Condant. f'oiv. Humati. (ruat. Ewe. Mare. Axs. 

S.G. I-OSIG 1-OS l-(«Or> l-()2ys 1-0317 1-036 

Water percent. 87-27 87-41 85-7) 80-82 90-78 89-6-t 

Casein. 3-02 1-03 3-20 4-rf7 1-24 0-67 

Albumen. 0-53 1-26 1-09 1-5.T 0-75 1-55 

Fat. 3-64 3-78 4-7S 6-86 1-21 I-6-t 

Milk Sugar. 4-88 6-21 4-4(! 4-91 5-67 5-99 

Ash. 71 0-31 0-76 0-89 0-35 0-51 

It has long been known that infants can digest human and asses' 
milk more easily than cows' milk cf. Jacobi, Jovni. Am. Med. 
As.swc/i. 51, 1216-1219 (1908). "Asses' milk has always been recog- 
nised as a refuge in digestive disorders, when neither mothers' or 
cows' milk, or its mixtures, were tolerated." 

From the above table we see that in cows' milk the ratio of 
albumen to casein is only 0-53 to 3-02, whereas in human milk it is 
1*26 to l'()3, and in asses' milk l"o5 to 0*67 (or over double the 
amount). " In cows' milk the casein forms 5/6ths of the total pro- 
teids in the milk, whereas in women's milk the casein forms 2/6th8 
of the total proteids." (Koplik, '■^Diseases of Infancy & Ghildhuod,'''' 
1902.) 

Human milk is hardly curdled at all by acid or rennin, the 
reverse being true with cows' milk. We see then, that the ratio of 
pi-otective colloid (albumen) to the irreversible coagulative colloid 
(casein) is a most important factor. 

" Cows' milk precipitates or coagulates very early with the aid of 
acids or salts ; women's milk quite late or not at all. Hence in the 
infant stomach, cows' milk does not take up much acid of the gastric 
juice and soon coagulates in large masses. Women's milk, on the 
other hand, takes up a large amount of acid of the gastric juice, and 
coagulates late in small masses. The differences in the modes of 
coagulation in the two cassins are of great importance in the study of 
infant feeding," (Koplik, loc. cit.) 

Cows' milk can be made to resemble human or asses' milk in 
protective qualities by the addition of such colloidal subtances as 
gelatine, gum-arabic, cereal gruel, or barley water (a staxchy solution). 
Very interesting observations with the ultra-microscope were made 
by Alexander and -Bullowa on this subject : — see Chein. News, 101, 
193 (1910). These authors followed the coagulation of milk by heat, 
rennin, and acids, with and without the addition of protective 
colloids, by the aid of the ultra-microscope. They concluded that 
" the casein of milk is an irreversible or coagulating or unstable 
colloid, which is protected by lact-albumen, a reversible or stable 
colloid," and further that " in the modification of cows' milk for 
infant feeding, it is necessary not only to consider the per cent, of 
total proteids, fat, etc., present but to see that the casein is adequately 
protected." (Luc. cit., p. 19.").) 

The fat present in milk is carried down by the curd resultant 
upon milk-curdling. The greater the extent of coagulation, the 
larger is the amount of fat carried down witli the curd, and since 
such fattj- curds tend to coalesce and give rise to large masses little 
amenable to the action of the digestive juices, it follows that 

20895 D 



98 HEPORTS ON THE STATE OF SCIENCE. 1918. 

protection of the casein by some agent such as albumen or gelatine is 
most advautaareous. 



^o^ 



Am. Chem. .Sot: 32, 080-87 (1910). 



I 
„ ) Auzol, T/te.se de Paris (19U7). 
■ J U.S. Puh. Health atid Mar. Hasp. Serv., Wa.shiMiton, Hijg. Lah. Bull. 41, 
( p. 658. 

A most interesting and comprehensive study of "The Coagulation 
of Cows' Milk in the Human Stomach " has been made by Brenne- 
mann {Arch. Pediatrics 34, 81-117 (11)17) ). 

He found that when fresh milk is drunk, the curds formed in the 
stomach are very large and hard, whilst milk boiled for 5 minutes 
gives ri^e to small soft curds. The curds become harder and bigger 
as the fat content of the milk is decreased. An increased fat content 
leads to smaller and softer curds, but their digestion is less rapid. A 
rapid ingestion of milk produces larger curds than does the sipping 
of milk. 

Diluted milk leads to finer, flakier, and more porous curds. Lime 
water and milk do not easily coagulate, even if at all. Barley water 
and other starchy decoctions, when added to the milk, lead to 
smaller curds, more easily digested; they exert a "protective" 
influence over the casein. 

Another phenomenon of great interest in colloid chemistry is 
exhibited when milk is boiled, or made, into milk puddings etc., 
namely, the formation of a skin or membrane at the surface. This 
subject has been investigated by Ramsden : — 

Arvhi.f. Anat. ii. Physiol., pp. 517-534 (1894). 
Pruc. May. Soc. 72, 156-164 (1903). 
Zeit. phi/s. Chem.\'^, 336 (1904). 

Ramsden asserts that for this membrane formation there must be 
l^resent a free (gas) surface, and a general system as follows : — 

water , ' dissolved colloid , ' gas. 

Particles of the dissolved colloid passing spontaneously out of 
the solution give rise to a delicate surface pellicle or membrane. 
Ramsden found that all albumins in time can form such a skin at the 
still surface of their solutions. The colloid lowers the surface 
tension of the liquid and passes into the surface layer (adsorption), 
the process being an irreversible one. Even dilute solutions can 
yield a highly concentrated surface layer, following definite 
mathematical relations ; see Milner (Phil. Mag. 1907 (vi) 13, 96). 

The Fat in Milk Cream. 

Milk contains about 3"6 per cent, of fat, present as an emulsion of 
fair stability. On standing, the greater portion of the fat rises to the 
surface, as cream, and the milk then contains about 0*2 per cent, fat 
(water = 90*4 per cent.). Much argument has taken place as to 
whether the fat globules in milk are surrounded by a membrane, or 
by a gelatinous mucoid substance, semi-liquid, usually referred to 
under the Danish name " slim-membran ". Storch claims to isolate 
this mucoid body by treating c'beam until all the lactose, casein, etc., 
has been washed away. Staining milk with ammoniacal picro- 
carmine, Storch examined the fat globules under the microscoi^e and 
observed a stain layer enveloping each globule. Though he claims 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 99 

this fact as additional evidence for his "slim-meinbran" theory, the 
modern notion of adsorption can account for such staining without 
assuming a mucoid surface at all. 

A milk from which the cream has been separated may be used as 
the medimn for emulsifying such oils as coconut oil, and cotton- 
seed oil, to yield artificial milks, emulsions of great stability. Such 
a result decidedly tends to disprove the notion of a mucoid substance 
being necessary for the existence of the fat in milk ^as small 
globules. 

Cream is formed by the rising of the fat globules through the 
denser milk serum to the surface. The density o£ the liquefied 
fat is about 0-92, whilst that of the milk serum is over unity. The 
diameters. of the fat globules vary between 001 mm. and 0-00l6mm. 
Thick cream contains about .56 per cent, fat and 39 per cent, water, 
whilst thin cream contains about 29 per cent, fat and 64 per cent, 
water. The fat content varies between very wide limits, and the 
percentage of fat is in inverse ratio to the density of the cream. 

Tlie purchase of cream is based on its thickness, which is usually 
measured by its viscosity. Thickness is often induced by the aid of 
such substances as gum tragacanth, gelatine, starch, " viscogen " 
(lime and sucrose-syrup), or by the process of homogenising, i.e., 
forcing the cream through minute orifices (at a suitable temperature 
below 60°C.) under pressure. {See section on homogenised milk.) 

Since it is impossible to whip cream which has undergone homo- 
genisation, gelatine, agar-agar, or gum tragacanth is added to. the 
extent of about 0-1 per cent., so as to induce permanent frothing 
on beating up the cream. It is interesting to note that homogenised 
cream cannot be churned into butter. 

Butter. 

When milk or cream is churned, the globules of fat coalesce and 
granules are formed, which are then worked together to give a mass 
of apparently homogeneous texture. The averasre fat content of 
batter is 83"5 per cent, fat and the water content about 13 per cent. 
When examined under the microscope with crossed Nicol prisms, a 
uniformly dark field is viewed, whereas margarine under similar 
conditions presents a dark field containing bright portions and 
indistinct crystalline structures. The fat in milk, on churning into 
butter, has no crystalline structure, whilst margarine fats have, 
owing to their repeated melting and cooling. 

As to the exact changes occurring when milk fat is churned into 
butter, there is still divergence of opinions. The upholders of the 
"slim-membran" theory, argue that the mucoid substance envelop- 
ing the fat globules is rubbed off, and the globnlos thereupon coalesce. 
Fleischmann inclines to i-egard the process of churning as being the 
solidification of superfused fat globules, but this theory is discredited 
by the fact that the fat globules in milk are rapidly solidifieil by 
mere cooling. 

It is very likely, however, that there is an adsorption layer of 
some kind around tae fat and that during churning this layer is 
continually thinned out by the impacts of the various globules, 
eventually permitting coalescence to small nuclei, which grow by 

20895 ( D 2 

i 



100 REPORTS ON THE STATE OF SCIENCE. 1918. 

degrees until that particular moment arrives when the butter particles 
suddenly become visible. There is still room for considerable 
physico-chemical research in connection with this long-known but 
little-elucidated phenomenon. 

The butter nuclei are v/orked up to a homogeneous mass, which 
the microscope shows to be a solid emulsion of fat, with fat the 
continuous medium, and water the disperse phase, an exact reverse 
of the system occurring in milk. (Compare section on " Margarine.") 

The physical conditions of churning, especially the temperature, 
exert a profound influence on the butter, particularly with regard to 
its moisture content. The main factors to be considered in this con- 
nection are the fat content, the acidity, and the viscosity of the 
cream, and the agitation employed. A cream containing 30 to 45 
per cent, of fat churned at a temperature ranging from 13°C. to 18°C. 
should give good results. As cream ripens, lactic acid is produced, 
the viscosity of the cream diminishes and churning becomes easier. 
In this connection it is interesting to note that acids tend to make 
emulsions " break," i.e., separate into oil and water, probably by some 
action on the protective (emulsifying) agent present. Here the 
casein is coagulated and precipitated if the acidity is too pronounced, 
and casein clots may be found in the butter mass. Churning must 
not be conducted too rapidly and violently, for then the moisture 
content will be too high owing to the enclosure of buttermilk within 
thei nuclei. Also churning must be stopped as soon as the butter 
granules reach the size of small peas, otherwise the granules will 
coalesce and retain an excess of buttermilk which cannot be washed 
out again. 

The physical chemistry of butter as a solid emulsion has been 
little studied, as indeed have any cases of solid emulsions, a matter 
which is referred to in more detail when discussing " Margarine." 

Casein. 

Casein is a phosphoprotein occurring to the extent of about 
3 per cent, in cows' milk and about 1 per cent, in humnn milk. It 
is combined with the phosphates of the alkaline earths yielding a 
pseudo-solution or very fine colloidal suspension. Some writers 
adojjt Halliburton's nomenclature and use the name " caseinogen," 
reserving the term " casein " for the curd produced by the action of 
rennet on milk. In this paper the term " casein " is used throughout 
(following Hammarsten). 

Casein is precipitated from milk by saturating with NaCl, 
MgS04, (NH4)oS04, and mineral acids ; also by tannin, metaphos- 
pkoric acid, phosphotungstic acid, CUSO4, ZnSO.i and by rennet. It 
is soluble in alkalies and in solutions or salts which hydrolyse to 
alkaline solutions, e.g., phosphates, and it is insoluble in alcohol and 
ether. 

When pure, casein is a white amorphous, odourless, tasteless solid, 
soluble in water to about O'l per cent. Though precipitated by 
mineral acids, it redissolves in excess of acid. Opalescent solutions 
are obtained when casein is dissolved in just the necessary quantity 
of sodium phosphate and a little CaClj ; some investigators believe 
this condition prevails in milk itself. 







Casein. 




f'ows'. 


Human. 


c 


52-69 per cent. 


.')2-24 per cent. 


•H 


6-81 


7-32 


N 


15-65 


14-97 „ 


S 


0-832 „ 


1-12 ., 


P 


0-877 ., 


0-68 „ 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 101 

The elemental analysis of casein derived from Cows' and from 
Human milk respectively are : — 



cf. Lane — Claypon 
''Milk and its Hy- 
gienic IlelaUons " 
(1916), p. 37. 

Casein is amphoteric in reaction, though its acidic functions are 
more pronounced, when it behaves as a tri-basic acid. When dis- 
solved in dilute alkali a Z-rotatory solution ensues. 

Exactly as to how casein exists in milk is still a debatable point. 
Some authors believe it exists as a salt of lactic acid, casein-lactate. 
That lactic acid and casein do unite was shown by W. Van Dam 
(Chem. WeekUad. 7, 1013 (1910)). This author, using Bredig's ethyl 
diazo-acetate method, determined the reduction of the H ions in 
solutions of lactic acid produced by adding various amounts of 
casein. The casein combined with a constant amount of lactic acid, 
viz., 4*25 per cent. 

lievis and Payne infer a combination of casein with calcium 
phosphate. Richmond adduces evidence " that casein exists in milk 
as a calcium sodium salt,.combined with one molecular proportion of 
tricalcium phosphate." {Dairy Chemistry (1914), p. 30). 

Casein is not coagulated when milk is boiled, but alterations 
occur in the molecule affecting the action thereon of digestive 
ferments, and in all probability increases the digestibility. 

At higher temperatures than boiling, casein suffers partial 
coagulation, e.g., at 130°-140° C, and Jensen and Plattner are of the 
opinion that the browning of milk so heated, is caused by the incip- 
ient breaking down of the casein." {Rev. gen. du Lait IV, 361-388 
(1904-5).) 

Cf. Also Conradi " Ueber den Einfiuss erhohter Temperaturen 
auf das Casein der Milch." Milnch. med. Wochensch. 48, 175 (1901). 

The estimation of casein in milk is made as follows : — 10 grs. of 
milk are diluted to 100 cc. and warmed to 42^" C. 1*5 cc. of a 10 
per cent, solution of acetic acid are added, and the mixture well 
stirred. The precipitated casein is allowed to settle for about 10 
minutes, filtered on to a tared filter paper, dried at 105° C. and 
weighed. Ignite, and subtract the ash, plus the ash of the filter 
paper, from the total weight. 

Casein is typically colloidal in nature as may be inferred from its 
behaviour in solution. It acts as a protective colloid, and stable sols 
of silver or cadmium sulphides are readily prepared by passing H2S 
through solutions of silver or cadmium salts containing casein. Its 
gold number (determined in solution in ammonia) is 0"01, which 
stands quite high in the list of protective colloids arranged in the 
order of their gold no., i.e., power of protection. 

Casein combines with a fixed amount of NaOH (1 gr. requiring 
0-88 millimol of NaOH) yielding a solution which has a normal 
electrical conductivity, but which does not pass through parchment 
when dialysed. 

20895 D 3 

/ 



102 REPORTS ON THE STATE OF SCIENCE. 1918. 

Chick and Martin showed that both acid and alkaline solutions of 
casein show an increase in viscosity as the amoiint of acid or alkali 
present is increased, indicating the greater adsorption of water by the 
casein-salt panicles than by casein alone. (Cf. Z. Chem. Ind. Koll. 
11, 102-105 (1912).) 

Casein adsorbs acids, the amount adsoi'bed being almost directly 
proportional to the acid concentration. (Cf. Tangl^ Chem. Zeit. 
(1908) 1, 1288.) 

The part played by casein in the colloid reactions of milk is very 
pronounced, and is discussed under "The Coagulation of Milk." 

The Coagulation of Milk. 

The coagulation or "curriling" of milk can be brought about by 
addition of acids, or by means of rennet, an enzyme obtained from 
the stomach of the calf. The casein in the milk is not acted upon by 
rennet in alkaline solutions, but only in acid or neutral solutions, 
and the greater the degree of acidity of the milk, the more rapidly 
does the rennet act. Dilution of the milk with water inhibits the 
action. 

The natural curdling of milk is due to the acidity produced by 
bacterial action, which sets free lactic acid. Various investigators 
have proved that it is the actual hydrogen ion concentration that 
matters, and not the nature of the acid. The time required for 
clotting is proportional to the hydrogen ion concentration. (Cf. 
Michaelis and Mendlessohn, Biochem. Zeit. 58, 315 (1915).) 

These investigators found that the optimum concentration of 
hydrogen ions required for the precipitation of casein by acids in 
pure solutions or in milk = 2-.5 x 10~^ The minimum concen- 
tration required was found by AUemann to be 1*3 x 10~\ (Cf. 
Biochem. Zeit. 45, 346-358 (1912).) 

Orla-Jensen showed that equivalent quantities of different acids 
are necessary to curdle equal quantities of the same milk at a given 
temperature, but the acids act at a different rate. (Cf. Oversiyt. K. 
Danike. Vidensk. Selsk. Forh., pp. 287-309 (1914).) 

The whole question of the coagulation of milk by acids, and 
especially by rennet, is intimately connected with the question of 
the calcium content of milk, and any complete discussion must 
commence from this point. 

In milk about 76 per cent, of the total calcium is combined with 
the casein ; the total calcium content amounts to about 0*18 per cent. 
That calcium which is not united to the casein (about 24 per cent.) is 
present as phosphate and citrate. (Cf. Trunz, Zeit. f. physiol. Chem.., 
40, 263 (1903-4), Rona and Michaelis. Bioohem.Zeitsch.,2h 114(1909).) 

When milk is heated, the calcium content falls. Thus Soldner 
showed that a milk containing 18 mgms. of Ca. per lOOcc. when cold, 
lost 14 mgms. (?>., 17"5 per cent.) on boiling ; in two other instances 
the loss amounted to 18 per cent, and 24 per cent, respectively. A 
similar decrease took place in the content of P2O5. Soldner inferred 
that the Ca. was united with phosphorus as mono- and di-calcium 
phosphate; this on boiling was converted into the insoluble tri-phos- 
phate, and so precipitated. (Cf. Soldner, Landw. Versuchs. (1888), p. 
351, Boekhout and de Vries, Landw. Versuchs. (1901), p. 221.) 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 103 

Grosser, Biochem. Zeit., 48, 427 (1913) took a sample of milk 
and filtered it through a Bechold filter under a six atmospheres 
pressure of nitrogen, thus removing the colloidal constituents. The 
filtered milk was analysed raw, and also after being boiled for 
15 minutes. The CaO content of the raw filtered milk was 23- 4 
per cent, of the initial (unflltered) sample, and after 15 minutes 
boiling, only 18-0 per cent., or a loss due to heating of 5 -J: per cent, 
of CaO. Repeating this experiment with butter-milk he found no 
change in the CaO content of the raw and the boiled filtrate, and 
inferred that the phosphorus and calcium had been spilt off from 
the casein owing to the acidity. 

When milk is boiled the decrease in the calcium content is 
accompanied by a rise in the hydrogen ion concentration ; see 
Milroy, Biochefn. Jour., 9, 215 (19*15). Approximately 8 per cent, 
of the total crude protein of fresh milk is not recovered by acid 
precipitation or heat coagulation. Cf. Palmer, J. Ass. Off. Agric. 
Chemists, 2, part I., 144 (191G>. 

Rennet Coagulation. 

When rennet is added to milk a separation into a precipitate 
(curd) and liquid (whey) takes place ; the casein is transformed to 
a dyscaseose, " curd " being the insoluble calcium compound of 
this, and to a caseose (soluble). Rennet can clot 400,000 times its 
weight of casein in milk (Hammarsten), but it is a most remarkable 
thing that shaking the rennet renders it inactive. Cf. Schmidt- 
Nielsen, Zeit. f. physiol. Chem., 60, 426-62 (1909). An aqueous 
solution of rennet can be separated into fractions, having varying 
capacities for curdling milk by filtration through porous clay. See 
Korschun, Zeit. f. phgsiol. Chem., 37, 366-76 (1902). 

Rennet acts best at 41° C, and the curd is then very firm ; a 
fluffy, soft curd results at temperatures between 15° C. and 20° C. 
(at which temperature only 18 per cent, of the milk is curdled), iind 
also at. 50° 0. (where 50 per cent, of the mdk is curdled). The 
optimum range of temperature is from 3^° to 45°. 

Rennet is rendered inactive by prolonged storage, by shaking, by 
heating to temperatures over 60° C., and by addition of alkalies. 

When milk is heated the action of the rennet is delayed, owing 
to the precipitation of calcium, but if CaClg be added, the coagulation 
occurs in the normal way. Milk deficient in calcium salts requires 
a longer time for rennet-coagulation to take place. Cf. Soldner, 
Landw. Versiwhs. (1888), p. 351 ; Ringer, Journal of Physiology, 
11, 464 (1890) ; Conradi, Miinch. med. Wuchensch., 48, 175 (1901) : 
Kreidl and Lenk, Biochem. Zeit., 36, 357 (1911). 

Interesting observations were made by Rupp, who observed 
that curdling by rennet was more rapid than with raw milk at 
temperatures between 55° C. and 65° C, but slowed down at about 
70° U. to nearly double the time ; in this case, however, a finer 
grained coagulum resulted. Cf. Bureau of Animal Ind. Bull., 
p. 166 (1913). 

Although boiled milk is not curdled by rennet, a coagulation 
occurs on the addition of small amounts of CaCl^. Lindet (Comptes 
JRendus, 157, 381 (1913)), suggests that this is due to the interaction 

20895 ' D 4 



104 llEPORTS ON TItE STATE.OF SCIENCE. 1918. 

of the CaCla "with the alkali phosphate and citrate in the milk, thus 
reducing the content of these, and rendering the casein less soluble. 

During the action of rennet there is no change in the hydrogen 
ion concentration, but this is raised by addition of soluble calcium 
salts, and decreased by addition of ammonium oxalate. It is 
interesting in this connection to recall the fact that rennet acts best 
in acid solution, i.e.. in the presence of hydrogen ions. It was 
shown by Van Dam by the determination of electrical conductivity 
that the coagulation time varied inversely as the hydrogen ion 
concentration, see Zeit. fjliysiul. Chem., 58, 295 (1908). 

Mellanby has advanced an interesting theory for the rennet 
coagulation of milk, assuming it is due to the adsorption of the 
enzyme by the casein, and the subsequent precipitation of the 
enzyme-casein complex by the bivalent Ca ions of the milk. The 
quantity of ionised Ca salt required to effect precipitation is 
intimately related to the quantity of the enzyme adsorbed. Cf. 
Jour, of Physiol., 45, 345 (1912). 

Bang observed that by adding rennet in fractions to milk, 
summation is noted, e.g., the coagulation time on adding 0*1 cc. of 
rennet to 10 cc. rnilk is 8 minutes, and on adding 0-2 cc. four 
minutes. If, however, 0*1 cc. is added, and 4 minutes later 
another O'l cc, then clotting occurs two minutes after the second 
addition. No such summation occurs if the milk, after the first 
addition of rennet, is heated to 65° C. 

Bang's many experiments led him to conclude that rennet is 
not a coagulating enzyme, since rennet of itself does not produce 
curdling, and the final act of curdling is not true coagulation, but 
is more akin to the precipitation of protein by neutral salts. Cf. 
Ivar Bang, Slmnd. Archiv. Physiol. (1911), 25, 105-144. 

Another conception of the rennet coagulation of milk is 
advanced by Schryver, Proc. Roy. Soc. (1913), B. 86, pp. 460-481. 
When solutions of calcium salts and sodium chelate are mixed, a 
clot results on heating. For salts which increase the surface 
tension of water, the greater their amount present, the shorter will 
be the time required for clotting to take place. Salts which 
decrease the surface tension decrease the time for coagulation, only 
up to a Certain limit of concentration, above which the time is 
increased, or the coagulation entirely prevented. The inhibition 
of coagulation is attributed to the adsorption of simple molecules 
by the more complex colloids which are thereby prevented from 
coalescing. In milk the necessary materials exist, but the adsorp- 
tion of simple molecules from the solution stops the coalescing. 
Schryver assumes that the enzyme clears the surface of the colloid 
from the absorbed substances thus permitting coalescence to occur. 
He asserts that in milk the" clot formation depends on the presence 
of four series of substances present, viz., simple inhibitory sub- 
Btances, colloids, enzymes, and calcium salts. 

Alexander advanced a somewhat similar notion, his view being 
that the casein is " protected " or held in stable suspension by the 
hydrophile colloid, lact-albumin, which rennet destroys, thus permit- 
ting the coalescence and precipitation of the casein particles. Cf. Wi 
Int. Cong. A^jp. Chem., 6, 12-14 (1912). 



I 



OK COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 105 

A very remarkable observation has been made by Kredil and 
Lenk (Biochem. Zeit., 36, 357, (1911)). They assert that sterile milk 
contained in sterile vessels will not clot when treated with sterile 
rennet. If, however, one dips into the mixture a non-sterilised body 
such as the finger or a glass rod, clotting sets in. A few drops of 
ordinary milk will also cause clotting. 

In conclusion attention is directed to a most interesting paper by 
Bordas and Touplain on " Reactions of Curdled Milk due to the 
Colloidal State " {Coinptes Remlus, 150, 311 (1910)), where the view 
is advanced that the reactions of curdled milk hitherto attributed to 
the presence of enzymes may be explained by the colloidal state 
of the casein. 

The Cellular Content of Milk. 

Milk contains a large number of cells, falling into three main 
classes : — 

(1) large uninucleated cells ; 

(2) multinucleated cells ; 

(3) small uninucleated cells. 

These cells are formed either from the epithelium of the gland, or 
from blood and lymph. They may be estimated by centrifuging a 
given quantity of milk, e.g., 10 cc. (preferably warmed to about 
70° C.) and examining th^ sediment by a microscope. Very varied 
results are given, thus Russell and Hoffmann obtained figures varying 
between 4,U00 and 1,000,000 cells per 1 cc. milk. 

C£. Hewlett, Jo?//-. 0//%/., 13, 87 (1913); Howlett and Cevis. Lauref.p. 85.% 
(1915) ; lloss, Jour, of Inf. Bhcaneis. 10) 7 (1912) ; Russell anii Hoifmaun, Jour, of 
Inf. DineagCK, 8, Suppt. (3), 63 (1910). 

Detailed knowledge of the nature of the cellular content of milk 
is still meagre, and the subject is only referred to here, as indicating 
another factor in the very complex colloidal nature of milk, since 
modern colloid chemistry is no longer the study of undialysable or 
glue-like substances, but of matter in a finely divided form, thus 
embracing grains, bubbles, capillary structures, animal cells, etc., 
and indeed any system of at least two phases, involving extensive 
surface areas. 

The cell content of milk is mainly of interest to histologists who 
are investigating its relation to disease in the cow. See " Public 
Health Dept., Washington. Reiiort No. 78 (1912)." 

Homogenised Milk. 

Homogenised milk is the term given to milk which has been 
heated to 50-60°C, and then forced under great pressure through very 
small orifices, thus red dicing the fat particles to very small diameters, 
e.<7., 1/lOOth of the original size. When such a milk is allowed to 
stand, practically no cream separation occurs at all, the milk remain- 
ing a homogeneous system. 

This change in the dispersity of the fat leads to phenomena well 
known in colloid chemistry. The extension of surface area of the 
fat leads to greatly increased adsorption of the milk serum, and the 



106 REPORTS ON THE STATE OF SCIENCE. 1918. 

fat s:lobules beai* a "condensed layer" which is very tenaciously 
held. The rising of the fat globules is thus inhibited and no cream 
separates. Again, one cannot churn homogenised milk, since churn- 
ing really implies the coalescing of the fat particles, and the separa- 
tion of the milk serum. 

The density of milk suffers no change on homogenising. The 
viscosity increases, due to casein adsorption by the fat globules, and 
the milk is thicker than ordinary milk of the same fat content. 
Wiegner reduced the average diameter of fat particles in milk by 
homogenising from 2-9fx to about 0'27;u. From viscosity measure- 
ments he calculated that in ordinary milk about 2 per cent, of the 
casein is adsorbed, whilst the casein adsorbed by the fat in homo- 
genised milk is about 25 per cent. 

No change is produced in the molecular disperse constituents of 
the milk, as is indicated by the fact that the electrical conductivity, 
and the osmotic pressure (determined by F. Pt.) show no change. 

If the homogenised milk is kept at a low temperature for some 
time the viscosity rises, and the fat particles do aggregate somewhat. 
Skim milk cannot be homogenised since it is nearly fat-free, and the 
casein present is already in a high degree of dispersity. Although 
mechanical means are of no avail, chemical means allow of this fur- 
ther dispersion of the casein, e.g., when NaOH is added to skim 
milk, the viscosity increases rapidly with the concentration of the 
alkali. 

Homogenised Cream. 

When cream is forced through an homogenising machine at a 
pressure of from 3,000 to 4,000 lbs. per square inch, the fat particles 
become extremely small, and the product is very viscous. Separation 
of the fat again is rendered almost impossible, even on centrifuging ; 
also it admits of neither churning nor whipping, and a colloid 
substance such as gum tragacanth must be added {e.g., 0*1 jjer cent.) 
before a pei-manent foam can be produced. (Cf. Koll. Zeit., 15, 
105-123 (1914).) Owing to its excessive' thickness, homogenised 
cream is utilised in making ice-cream, since a cream containing 
about 17 per cent, of fat will, if homogenised, serve in an ice-cream 
as effectively as an ordinary cream of fat content 25 per cent., the 
final product having as good a body and texture, as well as 
" creaminess." An objection to homogenised cream is its peculiar 
" starchy " flavour, this being more apparent, the higher the tem- 
perature at which homogenisation is conducted. 

The surface tension of homogenised milk is lovrer than that of 
the normal sample of milk. 

Artificial Milk. 

Of late years artificial milk has been prepaiect, and numerous 
patents taken out in this connection. It is simple enough to make a 
solution containing all the inorganic constituents of milk, but the 
organic (colloidal) constituents present a more difficult problem. 

Certain nuts and beans contain proteid substances closely akin to 
gluten or casein in properties, e.g. soya beans contain about 37 jjer 
cent, of such proteid matter, which can be brought into . colloidal 



ON COLLOID CI[EMISTRY AND ITS INDUSTRIAL APPLICATIONS. 107 

solution by boiling with alkali, or salts which react alkaline, e.g., 
sodium phosphate. 

Thus, von Riegler [Fr. Pat. 461131 (1913)], prepared an artificial 
milk by dissolving gluten in caustic potash. It is usual, however, 
to emulsify a small quantity of oil (say '6 per cent.) with this colloidal 
solution of casein, and then to add small quantities of lactose, lactic 
acid, citric acid, etc., to render the similarity to milk more complete. 
Other ingredients which find their way into artificial milks are 
dextrin, malt extract, sucrose, dextrose, honey, NaCl, NaH CO:i, egg 
yolk, and preservatives. 

Artificial milk can be "soured" by inoculation with lactic 
bacilli, and may be condensed, or made into artificial cream, butter, 
or cheese. Undoubtedly, a big future awaits this product, and it 
marks an especial advance in its use in margarine manufacture. 

For further details cf. : — 

Melhuish, Brit. Pat., 24572 (1913) ; Gossel, Fr. Pat., 451447 (1912), and Eng. Pat., 
27860 (1912) ; Monahan & Pope, U.S. Pat., 1104376 (1914) ; Y.Y. Li, Eng. Pat. 30275 
(1910) ; Kaufmanu, Eng. Pat., 7296 (1913) ; Liebrich, Eag. Pat., 12355 (189S) ; 
Melhuish, Eng. Pat., 9626 (1915) ; Beckmann m Dyck, U.S. Pat., 1216052 (1917). 

The Enzymes of Milk. 

Enzymes are colloids, constituting a special class of catalysts, the 
catalysts being living organisms. Their presence in milk gives rise 
to some interesting facts explicable along the lines of. our modern 
notions concerning colloid phenomena. The following enzymes are 
present in cows' milk : — 

(a) Peroxidase. 

(h) Reductase (indirect). 

(c) Catalase. 

{d) Amylase. 

There is no conclusive evidence of the presence of proteolytic 
enzymes, lipolytic (fat-splitting) enzymes, or of lactase. 

(a) Peroxidase. 

This enzyme is always present in cows' milk, and its destruction 
by heat furnishes the basis of numerous tests devised to distinguish 
between pasteurised and unpasteurised milks. The first test used 
was to add tincture of guaiacum and H2O2 to milk, when, if pei-- 
oxidase was-present, a blue colour appeared. This test depended on 
the fact that guaiaconic acid (present in guaiacum) oxidises to a blue 
compound. It is noteworthy that H2O2 alone does not give this 
coloration with guaiaconic acid ; an activator must be present to 
give the activating imi^ulse to H2O2 and then oxidation can take 
place. Such an activator is peroxidase the enzyme of oxidation. The 
active system, peroxide plus peroxidase, is termed an " oxidase." 

The enzyme is destroyed by heat ; also it behaves catalytically, 
since extremely large amounts of peroxides can be acted upon, 
provided an oxiJisable body be present. 

The guaiacum test is replacfed to a large extent by Storch's more 
reliable test involving the use of para-phenylene-diamine, and H2O2. 



108 REPORTS ON THE STATE OF SCIENCE. 1918. 

Cf. Ber. des. Versuchst. d. K. Vet. u. Landb. Hacks., Kopenhagen ; 
Milchztg., 27, 374 (1898). 

A grey-blue coloration is given. It is necessary for this test, how- 
ever, to use only 1 drop of HoOo inasmuch as boiled cows' milk gives 
a blue coloration with p-phenylene-diamine and H2O0, if the latter 
is present in sufficient quantity. This is owing to the fact that the 
casein interacts with an oxidation product of the amine giving a blue 
compound. Such a milk would not respond to the guaiacol test, 
unless a peroxidase were added. Cf. Nicolas, Bull. Sac. Cliim. 9, 
266-269 (1911-11). 

The importance of the " peroxidase reaction " in the colloid 
chemistry of milk lies in the fact that most investigators now believe 
peroxidase to be a peculiarly active form of colloidal iron or 
manganese hydroxide, held in solution by a protective (hydrophile) 
colloid. 

This protective colloid or emulsoid stabilises the system, and very 
likely confers specific properties such as coagulation by heat, acids, 
alcohol, etc. See Perrin, J. de Chim. 2Jkys., 3, 103 (1905); also, 
Rohmann and Shnamine, Biochem. Zeits., 42, 235-219 (1912). 

Wolff, in his " Contributions d la connaissance de divers pheno- 
menes ozydasiques naturels et artificiels'''' (1910), describes the full 
reproduction of all the actions of peroxidase with colloidal ferro- 
cyanide of iron. Similarly, Sjolleman made an artificial oxidase with 
a colloidal solution of manganese hydroxide. 

Lactic acid and hydrogen peroxide only interact very slowly ; if 
now, a trace of ferrous sulphate be added, oxidation proceeds very 
rapidly indeed. A similar acceleration of oxidation can be brought 
about by addition of peroxidase. Thus the close similarity between 
the true inorganic colloid and the enzyme is shown clearly. In fact 
an artificial peroxidase of marked activity was described by Dony- 
Henault, Bull, de la classe d. Sciences, Acad. roy. de Belgique, 
pp. 105-163 (1908), viz., A solution of 10 grs. gum-arabic, 1 gr. 
manganese formate and 0"1 gram, sodium bicarbonate in 50 cc. 
water, is treated with alcohol. The ppt. is redissolved and rei:)re- 
cipitated by alcohol. The precipitate contains colloidal manganese 
hydroxide keut in stable solution by the " protecting " gum-arabic. 

The " peroxidase reaction " is, no doubt, very closely connected 
with the iron content of milk, and it has been shown that there is 
quite sufficient iron in cows' milk to produce the reaction. The 
amount of iron in milk varies from 0"1 to 0'7 mg. per litre. Cf. 
Edelstein and von Csonka, Biochem. Zt., 38, 14-22 (1912). 

Sarthou, Jour, de Pharm., 2, 583 (1910), and 3, 49 (1911), showed 
that the peroxidase reaction can result when as small a quantity as 
•0002% of iron is present. 

The reaction is used in dairy laboratories to detect between raw 
and pasteurised milk, and although great differences of opinion are 
held as to the temperature at which the reaction is no longer given, 
it is generally agreed that milk pasteurised by heating to at least 
70° C. for about 15 minutes, renders the peroxidase inactive. Cf. 
van Eck, Zeit. f. Unters. Nahr. u. Genussm., 22, 393 (1911). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 109 

Other papers of much interest in the elucidation of the peroxidase 

reaction : — 

Fenton, TnuiK. Chcm. Sue, 65, 899-910 (189+). 
Euler aud Boliii, Z. f. phi/.s'wl. Chem., 57, 80-98 (1908). 
Herzo^' aud Meier, '/. I. phi/.^iol. Ch-.m., 73, 258-202 (1911). 

Bach aud Ohodat, Henchtc.d. Clwiii. Oe.s:, 37, 1312-1:^18 (1901). Arr/i.d. Srlencex 
Phijs. et Xat., Gimem, 37, 477. 

Arnost, Z. f. Untei-x. Nahr. u. (fe/iim-iii. (1905), IQ, 309. 

Bertranil, 'C. Reiulit.i. 124, 1.S55 (1897). 

Kastle and Porch, ./. of Jiiol. Chem., 4, 36l (1912). 

Kooper, Z. Unters. M'ahr. u. Geiiunsm., 23, 1 (1912). 

Leff manu, A/iali/d. 1898, p. 85. 

Sames, Mih-ltw. ZeatnM., 6, 462 (1910). 

SarChoa, Jouni. dc Plutrni.., 3. 49 (1911). 

Seligmann, Z.f. Jlyij., 50. 97 (1905;. 

Ufz, Z.j. ange.w. Chem., 16, 871 (190:i). Ot^xtfri: Chem. Zty. (1904), p. 916. 

Waentig, .Aih. a.d. liaise.rl. Geaumlh., 26, "'64 (1907). 

Weber, MUchzf,^. (1902), pp. 657, (J73. 

Wirthle, Chem'. Ztfj. (1903), p. 432. 

(i) Reductase. 

It has long been known that if methyhjne blue be added to milk, 
the blue colouration produced could often be destroyed by incubating 
the milk for a while, the time required varying with the samples of 
milk taken. The action is recognised as a bacterial one, and great 
efforts have been made to utilise it to measure the bacterial content 
of milk, but owing to the fact that only some, and not all, of the 
bacteria in milk are concerned in the reaction, the method was 
found very unreliable. 

Schardinger {Zeit. Unters. Nahrungs- und Genussmittel 5, 1113- 
1121 (l'J02) ) made some notable observations on the milk-reduction 
of methylene blue, establishing the following facts : — 

(1) Fresh milk alone does not reduce methylene blue. 

(2) Fresh milk to which an aldehyde {e.g. formaldehyde) has 

been added reduces methylene blue to the leuco or 
colourless base. 

(3) This decolouration does not take place if the milk has been 

boiled. 

(4) If bacterial development be permitted, there is no need to add 

aldehyde to milk to obtain the reduction of methylene blue. 

The reaction in the absence of aldehyde is now termed thy " direct 
reductase reaction," and in the presence of aldehyde, the " indirect 
reductase reaction." 

Bhardinger's M.B. reagent is obtained by diluting 5cc. of a 
saturated alcoholic solution of methylene blue with 19r)cc. of water. 
His F.M.B. reagent contains 5cc. saturated ale.; methylene blue + 
5cc. of 40 per cent, formaldehyde 4- I'JOcc. water. In each case one 
uses Ice. of the reagent to 20cc. of milk warmed to 45'^ to 50° C. 

The specific enzyme causing the reaction is termed " aldehyde- 
reductase " or " formaldehydase." 

It is inferesting to note that analogous reactions in inorganic 
chemistry are obtained, using the colloidal solutions of metals of the 
platinum group. Thus aqueous solutions of hypophosphites are 
oxidised on the addition of finely-divided palladium : — 

II3PO2-I-2H2O H:iP03+Ho-|-H ,0. 



110 REPORTS ON THE STATE OE SCIENCE. — 1918. 

Formaldehyde is unaffected by colloidal palladium, but in the 
presence of methylene blue, nitrates, indigo, or other easily reduci- 
ble bodies, the aldehyde is oxidised, and the reducible bodies act as 
" receivers " for the hydrogen. 

Bach, Arch. ScL phys., Geneve, 32, 27—41 (1911), assumes the 
existence of a pei-hydride of oxygen in the water, H4O, analogous 
to peroxides in the peroxidase reaction. Such a compound has 
never been isolated, and one feels that its assumption is not required, 
since the theory of the activation of the water by the enzyme amply 
meets the case. 

An enormous mass of work has been done on the Schardinger 
reaction, but a recent paper by Lee and Mellon {J. Ind. Eng. Chem. 9, 
360 (1917) ) ably summarises the present position. The conclusions 
reached are : — 

(A) Methylene blue as it occurs in Schardinger's reagent F.M.B. 

is not decolourised by : — 

(i) Normal freeh milk in less than 20 minutes. When 
decolouration was effected in 10 mins. or less, the 
milk was found to contain 1,000,000 or more micro- 
organisms per Ice. 

(ii) Milk pasteurised at 70' C. for 10 mins., unless 
approx. 48 hours have elapsed since the milk was 
pasteurised, or until the bacteria have had time to 
multiply sufficiently. 

(iii) Old milk in which formaldehyde had inhibited 
the growth of bacteria. 

(B) Schardinger's reagent, F.M.B., is as a rule decolourised by 

normal milk allowed to " age " under ordinary conditions 
of temperature for 24 to 48 hours. 

(C) Pasteurisation increases the time required for the d.e- 

colourisation of the reagent. 

(D) In general, no proportionality exists between the time 

required for the decolourisation of the reagent and the 
number of bacteria in milk. In a given sample, how- 
ever, a general relation seems to exist between the two 
'up to a given point of acidity. 

(E) Inasmuch as there is kg absolute parallelism between the 

niwiher of bacteria in the milk and the time required to 
decolourise the reagent, but that the relationship seems to 
exist in a given sample of milk, it would indicate that 
reductase is of bacterial action, but that not all bacteria 
found in milk produce this enzyme. 

(F) It seems probable that formaldehyde either gradually retards 

the action of the reductase or destroys it. 

Several very interesting observations on the Schardinger reaction 
have been made by various investigators. Thus : — 

Utz {Zeit. f. angew. Chemie (16), 871 (1903) ) showed that sour 
milk could be made to give the reaction by adding to it 
NaOH or other alkalies. 

Rullmann (Biochern. Zeit. (32), 446 (1911) ) showed that instead 
of HCOH one could use formic acid for the F.M.B". test. 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. Ill 

Rumer and Sames {Zeit. f. Unters. Nulir-n. (Jenussiii., (20), 
1 (1910)) showed that milk which failed to respond to 
the Schardinger test would do so if a small quantity (less 
than 1 per cent.) i>f ferrous sulphate were added. The 
ferrous sulphate solution must not be boiled. 

Bibliography. 

Ariip, Amili/sf. Jan. (1918). 

Bach, Jiior/icni.. Zeit. 31, ^^'^ (1911) and 33, 282 (1911). 

Uarthel, Zflt. f. Untcrx. Xahr- u. Geim.ssm. 21, r.l3 (191 1) ; Amli/sf, 36, 316 (1911). 

Bertin-Sans and Ganjoux, Rev. d'Hi/i). 36- -'.".S (1914). 

Burri and Kursteiner, Milcliw. Zeniralh. Q, 40 C1912). 

Cathcart and Hahn, Arcli.f. Ilyq. 44, 295 (19u2). 

Fred, Centralb.f. Bald. ii. (1912) 35, 17 ; Analy.st, 38, 62 (1918). 

Jensen, Rev. f/en. du Lait. Q. 33. 56, 85 (1906). 

Lagane, Bev. 'iVBijq. 36, 222 (1914). 

Neisser and Wechs'berg', Miiiir/i. wed. Work. 47, 1261 (1900). 

Paal and Gerum, Berichte d. chem. Gencll. 41, 805 (1908). 

Seligmann, Zeit. f. Uiiq. 58, 1 (1908). 

Shroetcr, Centraih. f. Bakt.ii. 32. 181 (1911). 

Siegfeld, Zeit. f. angew. Chem. 16. 764 (1903). 

Smidt, .Arch.'f. Hi'iq. 58. 313 (1908). 

Somerfeld, Hyg. Centralb 4, 1 (1908), 

(c) Catalase. 

This very remarkable enzyme is universally presnit in cow's 
milk. It acts on hydrogen peroxide to produce molecular' oxygen, 
this result being very unique, since one usually obtains 'active' or 
atomic oxygen when HoOq is decomposed. The generally-accepted 
explanation is that the enzyme attacks two molecules of H2O2 
simultaneously, thus : — 

2HOOH=2H20 + 02 

Catalase in milk is estimated by measuring the volume of oxygen 
liberated when a given quantity of H2O2 is added to a given quantity 
of milk. Usually one takes 20cc. of milk and 5cc. of a 3 per cent. 
H2O2 solution, using a special apparatus, which is kept in the w-ater- 
bath during the course of the test. 

The catalase is most probably of "bacterial action, and its amount 
increases when the milk grows stale. Cream contains a larger 
percentage of catalase than the rest of the milk. So far no figure for 
the normal catalase content of milk is agreed upon, though such a 
standard is desirable as an indication of the bacterial content of a 
given sample. 

Oxidising agents such as chlorates, nitrates, and hydrogen 
peroxide, and poisonous bodies like HON or mercuric chloride are 
especially harmful to catalase ; indeed, Euler has shown that a strength 
of 1 in 1,000,000 of HCN reduces the reaction velocity of catalase by 
one half. 

Bibliography. 

• 

Barthel, Zeit. f. Unfers. Xalir- it Gen>i«x»i. 15, 385 (1908). 

Bier, Maly'x Tien/,. 35, 230 (1905). 

Burri and Staub, Zeit. f. Uiiterx Xahr- u Genugxin. I7, 88 (1909). 

Chick, Centralb. f. Bakt. ii., 7, 705 (1901). 

Faitelowitz, Milch Centralb. 6, 299, 3(;i (1910). 

Gerber and Ottiker, iWM. Centralb. 6,316(1910). 

Giiforn, Bef. Bet: gen. dti Lait, 8, No. 22 (1911). 



112 REPORTS ON THE STATE OF SCIENCE. 1918. 

Harden and Lane-Claypon. Jmirnal of Htifi'iene.. \% 143 (1912). 

Kooy>er, Milcli. Centvalb.. 7,411,264(1911). 

Koning:. 3rdch. C^iitndh.. 3. 41. 53 (1007). 

Lam, Malifx Jin-r/i,., 36, 232 (1900). 

Neumann-Wender. Ocxferr. Clicm. Ze'itiuifi. g, 1 (1903). 

Kaudnitz. Errirhnif.-<c dcr Pliyaiolnqii' (1903) g. pc. 1. p. 274. 

Kullmann. Arch. f. Uiiq.. 73, 81 (1911). ' 

Sarthou. C. Rend us.. i\Q. 119 (11)10). 

Schroeter. Ceutralh. f. BaM., ii. 32, 181 (1911). 

Seligmann. Zcit. f. Hi/f/.. 5'>. 97 (1905) and 58, 1 (1908). 

Sinidt. Arch.f. Hi/g., 58- 313 (1908). 

Spindler, Biochem.'Zeit., 30, 384 (1911). 

For a detailed study of the enzymes of milk cf. Lane-Claypon, 
' Reports to the Local Go"vernment Board on Public Health and 
Medical Subjects ' (New Series), No. 76 {m'6). 

(d) Amylase. 

This enzyme is only present in small amount, e.g. Lane-Claypon 
found that lOcc. of cow's milk at 'dl^G hydrolysed about '001 to -002 
grm. of starch in three hours. The stai'ch is converted to dextrins. 

Koning found the amylase activity of milk to be destroyed on 
heating to 68° C. for 45 minutes. 

Margarine. 

Margarine technology presents many questions of great interest 
to the Colloid Chemist, and offers a wide field of research in pure 
physical chemistry. 

Margarine is a substitute for Butter, certain animal and vegetable 
oils and fats replacing the familiar butter fat. Thus stearin e, oleo, 
lard, cocoanut oil. palm kernel oil, cottonseed oil, and arachis, kapok, 
maize, and wheat oils are all in present use. The oils and fats are 
liquefied together in certain proportions, depending on the quality of 
the margarine required, and then chui-ned with soured milk to form 
an emulsion. This emulsion is rapidly cooled, either by means of a 
spray of iced water under pressure, or by flowing on to well-cooled 
revolving drums. The i^roduct in each case is then worked up in 
drums or rollers to the required buttery texti?re and conHietency. 

For an account of modern Margarine Technology, cf. Clayton, 
J.S.C.L, 36, 1205-1209 (I'.tlT). 

In the manufacture of margarine, the process of emulsification is 
of first importance. " The object of churning is to imitate the 
emulsion found in cream and milk, where the fat globules have 
diameters ranging from D'Ol m.m. to O'OOIG m.m. and remain as 
discrete particles. The general theory of emulsification indicates 
that with two immiscible or only partly miscible liquids, two types 
of emulsion are possible, each constituent being in turn the disperse 
and then the continuous phase. For concentrated solutions a third 
(emulsifying) agent is required. Where oil is to be the internal or 
disperse phase, the emulsifying agent should be capable of lowering 
the surface tension of the external or continuous medium, and should 
be viscous, as is glycerin, or an emulsoid, like gelatin. If oil be 
dispersed in water, a stable emulsion can be made, the stability 
depending on the minuteness of the oil drops, this in turn being a 
result of the efficiency of the emulsifying apparatus. If, however, 



ON COLT.OID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. .113 

water be dispeiBed in oil, a very unstable system is produced, separ- 
ation into two layers taking place as soon as beating-up ceases. Now 
milk by virtue of its colloidal content is an excellent emulsifying 
agent, when oil is the disperse phase. Consequently if milk be in a 
churn in bulk, and oil is slowly fed in, with continuous agitation, an 
excellent emulsion of great oil concentration can be produced, and 
will set to a homogeneous mass afterguards. But if the oil be in the 
churns in bulk, and milk is fed in, a very unstable system results, 
which easily separates into layers on stopping the agitation for a 
while. This has been proved many times and the explanation seems 
clear : — To get a suitable emulsion of water in oil, one would require 
an emulsifying agent which should form an «?'Z-soluble colloidal 
solution but in milk the colloids are 7/-'a/er-soluble. Both theory and 
practice condemn any form of churning which would lead to 
emulsion with oil as the continuous medium. Such emulsions when 
cooled by iced water, or on drums, solidify with clot formation, and 
the resultant margarines are ' spotted ' in texture." (Clayton, Loc. ciL). 

In order to aid emulsification many colloidal substances have 
been proposed for use in making margarine, e.g., starch, gelatin, 
glycerin, egg-yolk, lecithin compositions, etc. These agents are 
added to the milk, and certainly do have a most helpful etfect when 
churning. So small a quantity as O'l per cent, of glycei-ine added 
to the milk or oils (since it mixes with oils) leads to much improved 
emulsification. The usually-accepted theory accounting for this 
phenomenon is that the emulsifying agent forms a membrane or 
tilm around the oil globules and so prevents their coalescence. 

Egg-yolk, usually compounded in Sesame Oil, has been fairly 
widely used in margarine works as an aid to churning, and it is very 
interesting to note that egg-yolk, containing about lU per cent, of 
lecithin, and 15 per cent, albumen, both colloids, is an exceptionally 
stable emulsion, not separating into phases even on long standing or 
centrifuging. 

Pracrioally all the physico-chemical questions relating to mi^rgarine 
involve discussion of emulsions, and unfortunately rather too little is 
understood concerning them, whilst the physical chemistry of a. solid 
emulsion, such as margar-ine as a finished article presents, is only in 
its infancj'. 

The first question which arises is concerned with the determi- 
nation of the nature of the external, and disperse phases of a given 
sample of margarine, i.e., is it a solidified oil-water or watei--in-oil 
emulsion ? That is a hard question to answer. With liquid emul- 
sions the problem is easier, and three methods at least may be 
employed to differentiate : — 

(1) By a Kataplwresis test, since the internal phase being nega- 
tively charged will wander to the anode. 

(2) Indicator Mdliod. This method depends on the fact that if 
one adds an oil-soluble dye to an emulsion, the dye will spread if the 
oil be the continuous medium. Thus Robertson used Sudan III, a 
red dye, in his work on emulsions of olive oil in water (cf. Koll. 
Zeit.,T, 7-10 (1910).) With an emulsion of oil in water, the colour 
would not spread, but be confined to those globules of oil wi+h which 
the colour grains were actually in contact. 



114 TJEPORTS ON THE StATE OF SCIENCE. 1918. 

(3) Droj) Method. The principle involved is tliat one can dilute 
an emulsion by adding more of the continuous medium. {See 
Newman, Journ. Phys. Chem., 18, 34-55 (1914). ) 

Now these methods are not suitable for a solid emulsion such as 
margarine, though the staining with dyes, followed by an exami- 
nation of a thin film under the microscope, sometimes gives valuable 
indications. The electrical conductance of margarine, the heat con- 
ductance, and the viscosity would seem to offer suitable lines of re- 
search in this problem of distinguishing the nature of the phases. 

If the margarine were an oil-in-water 'emulsion, one would 
anticipate a possible electrical conductance (since there is at least 
1 per cent. NaCl present), on the same lines as the conductivity 
through a set jelly, e.g., gelatine. But with a Avater-in -oil emulsion, 
the conductivity (if any) would be very small indeed, inasmuch as 
the contiguous particles are now fat, which is characterized by its 
insulating properties. 

Again, it would ba rco.sit interesting to investigate the heat con- 
ductivity of two solid emulsions having inverted phases. The 
corresponding case of the heat conductivity of a set jelly still remains 
for research. 

Possibly information would be afforded by the viscosity of a solid 
emulsion. The role ef viscosity in colloid researches is increasingly 
manifested, and "the great importance of viscosity measurements as 
the most delicate means of tracing slight changes in colloidal solu- 
tions is fully recognized " (E. Hatschek). Indeed, with an emulsion 
like margarine, with an average ratio of oil to water, 3'6 : 1, one would 
anticipate notable variations in viscosity depending on whether the 
oils and fats constituted the disperse or continuous medium. 

There are many other problems of a colloid nature connected with 
margarine, but they are only apparent to one actually in contact with 
the entire process. Thus, why does soured milk yield a better 
emulsion with the oils and fats than sweet milk ? Certainly, no 
very sound theory is as yet proposed, though it is interesting to note 
that oils and fats containing a small percentage of free fatty acids 
will much more easily emulsify with water than will neutral oils 
or fats. Since sour milk is distinctly acid (lactic acid), there would 
seem to be some connection here, but mineral acids cause emulsions 
to " break." 

Finally, in connection with margarine manufacture, one research 
of great importance is suggested by the use of the various emulsify- 
ing agents previously referred to. So far, little work has been 
published describing wh^t one may term the ' emulsifying efficiency' 
of such an agent. Thus, to make a concentrated stable emulsion of 
an oil in water, one adds gelatine, starch, gum, flour, etc. It would 
be very interesting to arrange these substances in the order of their 
capacity or power of stabilising a standard-strength emulsion, and 
then investigating the possible connection between the " emulsifying 
efficiency " and the gold number, viscosity, surface tension, etc., of 
their pure solutions in water (cf. Moore & Krombholz, Brit. Juurn. 
Physiol. 22, 54 (1908) ). 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS . 115 

Chebsb. 

Cheese is obtained .by the rennet curdling of millv. The curd is 
cut up small and the whey expressed from it ; the mass is then 
salted and allowed to ripen by bacterial and enzymic action. There 
are many kinds of cheeses, but for the purpose of this paper their 
description is unnecessary. Very little indeed is known of the 
colloid chemistry of cheese, except that portion relating to the 
action of rennet on milk and the subsequent production of curd. 

The following are some typical analyses of hard cheeses : — 

ITjO. Fat. Protein. Ash. 

Per cent. Per cent. Per cent. Per cent. 

(a) Stilton... 20-30 44-00 . 23-70 2-75 

(b) Cheshire 34-70 33-30 26-10 4-30 

(c) Cheddar 33-90 29-05 ,27-37 4-05 " 

The structure of cheese varies from a dough-like to a granular 
texture, and it is in this connection that the only colloid researches 
have been made on cheese. 

Van Dam investigated the swelling of casein under the influence 
of common salt and lactic acid. He ascertained the solubility of 
casein in solutions of NaCl (5, 3, and 1 per cent.) containing lactic 
acid, and obtained curves showing the relation between the dissolved 
casein and the concentration of the hydrogen ions. Cf. van Dam, 
Gedenkhoek. aan J. M. van BemmeLn (1910), pp. 102-107. 

Chick and Martin published results on the viscosity of casein 
sols, which bear somewhat on this problem. In the case of both 
alkaline and acid casein solutions, the viscosity increases with the 
quantity of alkali or acid present, which indicates that the casein- 
salt particles have a greater adsorptive power for water than has 
casein itself. Cf. Z. Ghem. Ind. Koll. 11, 102-105 (1912;. 

The most important contribution to the subject, however, has 
been made by AUemann and Schmid (Landw. Jahrh. Schweiz. 30, 
357 -383 (1916) ). They investigated 'the elasticity of the coagulum 
produced in milk by rennet.' 

An apparatus was employed which measured the resistance 
which the curd offered to a vertical rod carrying three concentric 
rings. Thus they were able to investigate the effect of time, con- 
centration of rennet, concentration of acid, and other factors, on the 
curd produced. It was found that the elasticity of the curd 
increased in direct proportion to (a) acidity of milk, (b) concentra- 
tion of the rennet, {c) addition of soluble calcium salts, (r/) rise in 
temperature. No apparent maximum of elasticity was ascertained 
with ascending temperatures, though the time required for coagula- 
tion • reached a maximum at 41° C. Agitation during curdling 
inhibits the velocity about 8 per cent. With cold milk, a longer 
time was required for curdling, and the resulting curd had a 
decreased elasticity. 

The whole question of the structure of cheese still remains open 
for research, as also does the question as to the physical state of the 
fat globules present. See Stocking, 'Manual of Milk Products', 
chap. 9 (1917). 



116 beports on the state of science. 1918. 

Icb-Cream. 

Ice-cream manufacture provides an interesting case of the prac- 
tical value of the so-called ' protective action ' of colloids. 

Alexander {J.S.G.I. 28, 284 (1909)) writes :— ' It is a well-known 
fact to practical ice-cream, makers and amply proven by experience, 
that ice-cream made without eggs, gelatin, or some similar colloidal 
ingredient, is gritty, grainy, or sandy, or else soon becomes so on 
standing, whereas ice-cream made with small quantities of colloids 
possesses that rich, mellow, velvety texture, so much in demand.' 
(Cf. also Alexander {Zt. Chem. Incl. Koll., Feb., 1909).) 

Now ice-cream contains casein, and the action of the added 
(hydrophile) colloid is to ' protect ' it from coagulating. Gelatin 
JS especially advantageous, and as little as 0'5 per cent, suffices to 
render the ice-cream smooth in texture. Incidentally, the diges- 
tibility is increased too by addition of gelatin. (Cf. discussion on 
the digestion of milk curd in the stomach.) Besides the protection 
of the casein, it is most interepting to note that the small ice crystals 
are also ' protected ' by the colloidal binders added. An ice-cream 
having been whipped during freezing, contains numerous small ice 
crystals which on standing coalesce to form coarse grains. This 
coalescence is decidedly inhibited by gelatin, gum tragacanth, and 
starches, thus retaining the smooth texture so desirable in a first 
grade product. (Cf . Stocking '■Manaul of Milk Products,' Chap. 14, 
(1917).) 

An interesting paper on ' The Effects of Binders upon the Melt- 
ing and Hardness of the Ice-Cream,' was published by Holdaway 
and Reynolds {Virginia Expt. Stat. Bull. 211, 3 (1916) ). It is here 
shown that as the per cent, of fat in plain ice-cream increases, the 
cream becomes softer, and if too much fat is present a soft fluffy 
product results owing to ' wbij^ping.' Ice-cream made from 8 per 
cent, cream was no harder than from 19 per cent, cream, while 
30 per cent, plain cream was much softer than either. The fat, 
however, raises the melting point. 

Now if gelatin be added a harder ice-cream results, "wuth a 
higher melting point. The hardest and most heat-resisting cream is 
given by a medium per cent, of fat and a large amount of gelatin. 
Gum tragacanth (also a protective agent) may be used, in which case 
the ice-cream produced is harder- than usual (plain) but softer than 
when gelatin is used. One would expect this result, since the 
protective powers of the two colloids are very different, as will be 
seen by a comparison of their gold-numbers, viz.: — 

Gelatin 0-005 to 001. 

Gum tragacanth ... ... ... about 2"0. 

If too much gum tragacanth is used, a very slimy cream results ; in 
any case it is far inferior to gelatin ice-cream of any composition. 

Some manufacturers use starch as the agent to ' smooth ' their 
ice-cream, but although a better product than normal (plain) cream 
results, the texture is much more grainy than the ice-creams contain- 
ing gelatin or gum. One expects this to be the case, since starch is 
only a poor protecting colloid, the gold value of wheat starch being 
about 5, and of potato starch about 25. 



ON COLLOID ^CHEMISTRY AND ITS INDUSTRIAL APPIJCATIONS. 117 

Eggs are, of course, good binders, since egg-albumen (with a gold 
value of 0*15 to 0"25) is a strongly-protecting colloid. 

In the literature concerning ice-cream one finds the term 'filler' 
applied to these added colloids, but the term 'binder' is pi-obably 
to be preferred. 

This problem once again opens up the question as to the ultimate 
action of a protecting colloid ; the usually-accepted idea is that the 
colloid forms a membrane around the particles of the suspension 
material and so prevents the coalescence. This is Bechold's adsorp- 
tion view. (Cf. Zeit. phys. Ghem. 48, 385 (1904) ). 

[The question of ' protection ' is considered in detail in W. D. 
Bancroft's report upon Peptization and Precipitation, Cf. p. 2. 
W. C. M'C.L.] 

COLLOID CHEMISTRY IN PHYSIOLOGY. 
Bi/ Professor W. M. Bayliss, F.R.S., University College, London. 

Introductory. 

Since all physiological processes occur in complex heterogeneous 
systems, both coarsely heterogeneous and colloidal, it is clear that a 
complete discussion of the subject would include practically the 
whole of the science. Even in the functions of the central nervous 
system, which might seem most distant from colloidal chemisti-y, w^e 
have to take account of the properties of the membranes which inter- 
vene between the component elements, and certain observations made 
on these elements themselves will be referred to incidentally in the 
following pages. There are, however, some regions in which col- 
loidal properties play a more obvious and better known part. These 
concern especially the nature and properties of protoplasm itself, 
including the membrane which surrounds it, and the relationship 
of their constituents to electrolytes. Another problem that will 
appropriately be considered is the nature and functions of enzymes, 
which regulate the chemical reactions of the living organism. And 
finally, the remarkable properties of haemoglobin in relation to the 
transport of gases require brief consideration. 

Bibliography. 

Bayliss, W. M. (1918), 'Principles of General Physiology.' Second Edition. 

Chapters I, III, IV, V and X. (^Long-mans and Co.) 
Mathews, A. P. (1916), 'Physiological Chemistry' — especially pp. 190 to 205. 

(Bailliere and Co.) 
McClendon, J. F. (1917), 'Physical Chemistry of Vital Phenomena,' pp. 240. 

(Princeton University Press.) 

I. Protoplasm and Cell Contents. 

When a simple unicellular organism, such as amoeba, which 
consists of so-called " naked " protoplasm, is examined under the 
microscope, it is seen to contain a variety of granules and other 
inclusions of comparatively large size. These lie in a clear, apjiar- 
ently structureless, substance which is in contact with the water in 
which the animal lives. For this latter reason, the protoplasm is 
said to be naked, in contradistinction to vegetable cells, such as 
algae, which are clothed with a cellulose coat. 



118 REPORTS ON THE STATE OF SCIENCE. 1918. 

Since the amoeba and the water are two distinct phases, which 
do not mix, there is a surface tension at the interface of contact. 
Owing to the curvature of the surface being concave towards the 
animal, this surface tension results in a pressure exerted on the con- 
tents. Now the tension can be lessened by the addition of various 
substances to the water and, when this takes place locallj', a protru- 
sion is brought about by the internal pressure due to the higher 
tension of other parts of the surface. Under the ordinary microscope, 
these protuded portions, " pseudopodia," appear to be clear and 
structureless like water. This fact can be seen in the drawings made 
by various observers. But when they are examined by the brilliant 
lateral illumination of ultra-microscopic methods, light is diffracted 
by minute particles which are present in great number. These 
become visible as bright shining dots against the dark background. 
The general effect, when the illumination is at its best, is that of a 
multitude of brilliant ])oints in rapid, shimmering motion, occasion- 
ally more distinctly vibratory. This is the phenomenon first seen by 
the botanist Robert Brown in 1828 and hence called "Brownian 
movement." Its nature has been cleared up by Perrin, in a masterly 
series of researches, now well known. It was shown to be due to 
irregular bombardment by molecules of the liquid in which the 
particles are immersed and only present when the mass of a particle 
is small enough to enable the difference between the resultants of 
the unequal bombardment on opposite sides to be great enough to 
move it. The chief observations on Brownian movement in proto- 
plasm are due to Gaidukov (1910) and to Price (1914). 

The observation shows at once that protoplasm in its simplest 
form is a liquid, because otherwise particles present in it would not 
be free to move. The existence of these particles in the liquid shows 
that we have a colloidal solution of the kind called by Graham a 
hydrosol, which consists of a suspension of minute particles of a 
solid in water, or of an immiscible liquid in water. In other words, 
protoplasm is a dispersion of a more solid phase in a more liquid or 
watery phase. 

It is necessary to emphasise this fact, because earlier observations, 
made on cells which had been coagulated by the action of heat or of 
precipitating reagents, were believed to show the presence of a con- 
tinuous network. Although it is possible that a network might be 
produced under such conditions, it is to be remembered that, owing 
to the similarity in refractive index and in colour of the two phases, it 
is impossible to examine such preparations under conditions of illum- 
ination adequate to eliminate diffraction images, which readily take 
the form of networks when a regular series of dots is examined. 
The work of Hardy (1899) and of Alfred Fischer (1899) has shown, 
moreover, that a great variety of structures can be produced by the 
action of fixing reagents on cell protoplasm. It is impossible to say 
which of these corresponds to the living state. Most probably none 
do so, since we know that living protoplasm is a liquid. 

There is further evidence that this is the correct statement. 
When the cell of an alga is taken in as food, water is either taken 
with it or is excreted around it. Whatever may be the shape of the 
particle itself, the shape of the liquid drop in which it floats is 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 11!) 

ulwaj'S spherical. In other words, it takes the form conditioned by 
the free play of its surface tension. This would not be possible 
unless it were free from the constraint exerted by solid structures. 
A similar conclusion may be drawn from the shape assumed by a 
mass of protoplasm when stimulated in any way ; this is also spherical. 
Arthur Lister (1.S8S), a^ain, found that Badhamia, an organism 
which, at one stage of its existence, takes the form of masses of 
flowing protoplasm, filled with the brown spores of a fungus on 
which it feeds, can be filtered clear through wet cotton wool. It 
seems impossible that anything but a liqliid could be separated up 
into the fine threads necessary to pass through the cotton wool and 
reunite again into its original form. Chambers (11)17) has introduced 
some beautiful methods of micro-dissection. He finds that the 
needle can be repeatedly drawn through protoplasm without injuring 
it in any way. Very little resistance due to viscosity is experienced, 
as shown by the fact that it is only the granules in immediate 
contact with the needle that are displaced. There is no trace left 
behind in the track of the needle. 

It is remarkable that the only constituent cells of the tissues of 
higher animal organisms that have been examined in the living state 
by ultra-microscopic methods are those of the central nervous system. 
This has been done by Mott (1912) ?,nd by Marinesco (1912), 
independently. They agree in the statement that the protoplasm of 
these cells shows numerous particles in Brownian movement and is 
therefore a liquid. There is no sign of the large masses ('Nissl 
granules') nor of the 'neuro-fibrils' seen in fixed and hardened pre- 
parations. According to Mott, the " granules " themselves consist of a 
hydrosol, surrounded by an envelope which stains deeply with 
methylene-blue. Marinesco was able to see local reversible changes 
taking place spontaneously. Areas of more brilliant, tbat is, larger, 
particles appeared now at one part, now at another of the cell. 

While the state in which protoplasm "usually is seen is that of a 
hydrosol, certain observations made by Kiihne (ISt)!), by Gaidukov 
(1910), and by Price (1914) indicate that it may take on, temporarily, 
the state of a gel. In this state the Brownian movements are 
arrested, because the particles become fixed in position. It is evi- 
dently related to functional activitj". I have myself been able to 
produce it by weak electrical stimulation. What one sees is a 
sudden cessation of the shimmering movement, as if frozen solid. 
The condition is very transitory and requires careful adjustment of 
the illumination to show it. Price (1914) describes the protoplasm 
of a resting spore as being in the gel state, changing to the hydrosol 
on germination. When a cell dies it passes to the hydrogel con- 
dition. It is of some interest to .note that the pi-otruded pseud d- 
podium of an amoeba remains in the hydrosol state, a fact which 
suggests that it is produced by external influence rather than by a 
" vital" reaction on the part of the animal. 

What do wf know of the mechanism by which such changes 
might be produced ? There are two researches in particular which 
throw light on the question — that of Hardy (190t)) on gelatin and 
that of Clowes (1916) on emulsions of oil and water. Hardy ex- 
amined under the microscope the phenomena which occur when a 



120 KEPORTS ON THE STATE OF SCIENCE. 1918. 

warm gelatiu sol sets to a gel on cooling ; the first sign of change is 
that the ultra-microscopic droplets of the dispersed phase unite to 
form larger drops. If the solution is moderately concentrated, these 
drops unite together to form a network, but the watery phase is still 
continuous. On the other hand, if we begin with a solution of high 
concentration, the drops which first separate can be seen by their 
refraction to consist of the watery phase, so that the phase relations 
are reversed when compared with the former kind of gel. Thus the 
network may consist either of the more solid or of the more liquid 
phase. The properties vary accordingly. If the liquid phase is Ihe 
continuous one, it can be pressed out by squeezing. If the more solid 
constituent is the continuous phase, liquid cannot be pressed out 
except by a pressure sufficient to filter it through the more solid 
phase. 

The work of Clowes took its departure from an observation of 
Bancroft (11)13) that a mixture of oil and water can be made into a 
permanent emulsion in two ways. One of these consists of drops of 
oil suspended in a continuous watery phase, as in cream ; the other 
is of drops of water suspended in a continuous phase of oil, as in 
uutter. The former system is px'oduced when sodium soaps are used 
as emulsifying agents ; the latter if calcium soaps are used. Clowes 
(1916) showed that an emulsion of the former kind could be con- 
verted into one of the latter by shaking with a solution cf calcium 
chloride, while the latter could be changed into the former by 
shaking with sodium hydroxide. The changes may perhaps be 
realised by the illustration of a set of islands joining together so as 
to be transformed into a series of lakes surrounded by land. Clowes 
describes furfher experiments which will be more appropriately 
discussed in the section dealing with the cell membrane. He shows 
how the nature of the system depends on the relative surface 
tension at the two sides of the soap film which is formed by adsorp- 
tion at the boundary surface between the two phases. It will be 
obvious that the physiological properties of the two kinds of system, 
the liquid and the gel, with the possibility of converting one into 
the other by phase reversal, must play an important part in cell life. 

That there are possibilities of the formation of membranes, 
doubtless of a gel nature, within the protoplasm of a cell is shown by 
the fact that diiferent reactions can take place at the same time in 
different parts of the cell, notwithstanding the general liquid 
nature of its contents. The view that the organization of the cell is 
of the nature of many minute factories, in which various operations 
are being carried on under the influence of the structure of the 
cell, is at the present time rapidly displacing that of " giant " mole- 
cules with " side-chains," which were supposed to be continually 
split off and exchanged for other chemical groups. The question is 
discussed in the British Association address of Prof. Hopkins 
(1913). Put in another way, limitation of the point of view to 
that of pure structural organic chemistry is showing itself to be 
incapable of explaining physiological reactions. Protoplasm is an 
extraordinarily complex heterogeneous system of numerous phases 
and components, continually changing their relations under the 
influence of electrolytes and other agents. 



OS cor,r,oiT) chemistuy and its inditstrial applications. 121 

It has frequently been felt to be a difiBculty, from the standpoint 
of energetics, that cells use energy for purposes in which it is not 
easy to make out what has become of it. Warburg (1914) suggests 
that it may be required for the keeping apart of substances which 
would mix by diffusion, for the preservation of semi-permeable 
membranes, the restriction of osmotic interchange and so on, all 
of these phenomena being manifested in microscopic or even ultra- 
microscopic dimensions. A discussion of phase relations in proto- 
plasm in connection with equilibrium and energy will be found in 
the essay by Zwaardemaker (1906). 

A property of emulsoid colloids which has its importance in the 
present connection is their capacity of taking up water by what is 
ofien called " imbibition." The distribution of water between the 
two phases can be varied to a large extent by the presence of 
electrolytes and other agents. Whether imbibition is mainly or 
entirely an adsorption of water at the surface of the constituent 
elements, as is indicated by the experiments of Posnyak (1912) and 
by some which 1 did myself on gelatin (" General Physiology," 
p. 101), it is clear that the concentration of solutes in the liquid 
phase must be raised thereby. Since tlje position of equilibrium in 
reversible hydrolytic reactions, catalyzed by enzymes, depends on 
the concentration of water present, we see how at one time a 
synthetic product, such as glycogen, is hydrolyzed, and at another 
time glucose is synthesized to glycogen by the same enzyme. What 
is required is merely a means of varying the free water, and the 
possibility of this is provided by the presence of highly dispersed 
emulsoid colloids. 

In addition to the highly dispersed systems discussed above, 
protoi^lasm usually contains various larger aggregates and structures. 
Chambers (1917) calls the small particles visible under the ordinary 
microscope, " microsomes," and the larger ones, " macrosomes." He 
shows that the former are stable, the latter very sensitive to 
injury. There are also certain granules, of various forms, called 
'mitochondria.' Cowdry (1916) has devoted special attention 
to these and finds that they are stained in the living state by dyes ■ 
which contain a diethyl-safranin group, such as Janus-green B, and 
are apparently composed of albumin and lecithin. Ih the living 
state they are cqntinually changing shape, and especially in cells 
during activity. 

In the present state of knowledge, it would be unprofitable to 
speculate further on the functions of these different inclusions. 
The same may be said of the nucleus of the cell. That this is 
essential to continued life, growth, and subdivision is clear. Much 
attention has been given to the series of changes which it under- 
goes in the last process, called "mitosis," or " karyokinesis." They 
are obviously due to the ordered arrangement of certain vectorial 
forces, having a definite focus of origin, but we are still in the 
dark as to their meaning. Much imi)ortance has been attached to 
the number of distinct staining elements, " chromosomes," produced 
at a particular stage of the process. 

Unwarranted conclusions are sometimes drawn as to the chemical 
nature of substances found in cells from their behaviour to dyes. 



122 REPORTS ON THE STATE OF SCIENCE. 1918. 

The theory of dyeing has been described in an earlier report by 
King (1917) to which the reader may be referred. There are many 
factors which play a part in addition to chemical composition. 
Fischer (18'.>9) bas shown that the same substance stains diiferently 
according to the size of the particles in which it is found. The sign 
of the electric charge is also of importance. The meaning of the 
facts is still obscure. Nervous substance has a special ''affinity " for 
methylene-blue and other thiazine dyes, but also for some safranin- 
azo dyes, which have no chemical relationship to the former. 

Bibliography. 

Banceoft, W. D. 0',»13), '.Journ. Physical Chem.', 17, oOl. 

' The Theory of Emulsificatiou.' 
Chambers, Rob., Jr. (iyi7), ' Amer. Journ. Physiol.,' 43, 1- 

' Microdissection Studies, i. The Visible Structure of Cell Protoplasm and Death 
Changes.' 
Clowes, G. H. A. (1916), ' Joorn. Physical Chem.', 20, •t07. 

'Protoplasmic Equilibrium '. 
CowDUY, E. V. (igiG), 'Amer. Journ. Anat.', 19, 12;^. 

' The General Functional Significance of Mitochondria.' 
FisCHKE, Alfred (1899). 

' Fixierung, Ban und Farbun»- d«s Protoplasmas.' Jena, 
Gaidukov, N. (1910). 

' Dunkelfeldbeluchtung und Ultramikroscopie in der Biologic und in der 
Medizin.' Jena. 
Hardy, W. B. (1889), ' Journ. Pnysiol.,' 24, IcS. 

' Structure of Cell Protoplasm.' 
Hardy, W. B. (1900), ' Journ. Physical Chem.', 4. 254. 

' The Jlechanism of Gelation in Reversible Colloidal Systems.' 
Hopkins, F. G. (1913), ' Brit. Ass. Reports (1913),' 652. 

' The Dynamic Side of Biochemistry '. 
King, P. E. (1917), ' First R,ep. on Colloid Chemistry and its Industrial Applications.' 
Brit. Ass., p. 20. 

' General Review and Bibliography of Dyeing,' 
KUEHNE, W. (1864), 

' Unter.-!. iiber das Protoplasma.' Leipzig-, 158 pp., 8 plates. 
Lewis, M. R., and W. H. (1914), ' Amer. Jouru. Anat.', 17, 339. 

Mitochondria and other Cytoplasmic Structures in Tissue Cultures.' 
Lister, Arthur (1888), ' Ann. of Botany ', 2, 1. 

' Notes on the Plasmodium of Badhamia iitrivularis and Brefeldia maxima.^ 
Marinesco, G. (1912), 'Kolloid. Zeits-chr. ', H, 209. 

' Forsch. iiber den kolloiden Ban der Nervenzellen und ihre erfahrungsgemassen 
Veranderuugen.' 
Mott, F. W. (1912), ' Brit. Med. Journ.', Sept. 28th, 1912, p. 780. 

' The Bio-Physics and Bio-Chemistry of the Neurone.' 
Posnyak, E. (1912), ' Koll. Chem. Beihefte,' 3, 417. 

' Ueber den Quellungsdruck.' 
Price, S. R. (1914), 'Ann. of Botany,' 28, 601. 

' Some Studies of the Structure of the Plant Cell by the Method of Dark Ground 
Illumination.' 
Warburg, Otto (1914), ' Ergeb. Physiol.' 14, 253. 

' Beitrage zur Physiol. dt»r Zelle insbesondere iiber die Oxydationsgeschwindig - 
keit iQ Zellen.' 
Zwaardemaker, H. (1906), ' Ergeb. Physiol,' 5, 108. 

' Die im ruhenden Korper vorgehenden Energiewandlungen.' 

II. The Nature and Permeahility of the Cell Membrane. 

Although protoplasm is a hydrosol of low viscosity, it does not 
mix with water, remaining, while alive, as a separate phase. If 
"killed", as by an electrical shock or the application of an anses- 



ON COLLOID CHEMISTRY AND ITS INDTTSTKIAI, Al'l'MCATIONS. 123 

thetic, it freely mixes with the surrounding watery solution. In the 
normal state, it must be surrounded by a film or membrane of some 
kind, which prevents escape of the cell contents. We may draw a 
similar conclusion from the fact that the products arising from 
digestion of the food particles in protozoa, although consisting of 
such ireely diffusible substances as glucose and amino-acids, are not 
washed out. Much discussion has arisen as to the nature and even 
the existence of such a membrane. In the present Report, space will 
not permit of discussion of all the work which has been devoted to 
the problem. Attention must be directed to those aspects of it which 
appear to the writer to be of essential importance and to the conclu- 
sions to be drawn therefrom. These conclusions will sometimes 
differ from those of the investigators themselves and the reader may 
not always be inclined to agree with the interpretations given in this 
place. 

It has been pointed out (Bayliss, "General Physiology " p. 128) 
that, according to the Principle of Willard Gibbs, which is a con- 
sequence of the tendency of free energy to decrease, as stated by the 
second law of energetics, if there are in the cell contents any 
substances which lower surface tension, these must be concentrated 
at the interface between the protoplasm and the surrounding liquid. 
Moreover, Ramsden (1904) has shown that, in many cases, as solutions 
of bile salts, quinine or saponin, this concentration at the surface 
may be so great as to exceei the solubility of the substance in 
question, which is then deposited in a solid form, pi-oducing a film 
of more or less rigidity. In addition _to this, Chambers (1917) finds 
that the extreme outer layer of the protoplasm has the properties of a 
gel. The change from sol to gel has been discussed in the preceding 
section. In the jvresent case, it is doubtless due to the molecular 
forces at the surface. It should be noted that this outer layer of the 
protoplasm is not identical with the membrane to which the cell 
owes its semi-permeable properties. When a dye is unable to enter 
a cell, it does not stain this " hyaloplasm " stratum, so that the 
membrane which stops it has a more external situation. We see that 
there is every reason to expect the presence of a film on the surface 
of cells and that it would be reversible, existing only on the boundary 
surface and formed anew whenever any fresh surface is produced. 
These considerations also give us a clue as to the chemical composition 
to be looked for. In addition to the components of the hydrogel, 
whatever they may be, but almost certainly protein of some kind, we 
shall expect to find more especially those constituents of the cell 
which lower the surface tensicm of water to a marked degree ; in 
other words, all compounds of a fatty nature, and of these lecithin 
is known to be universally present. 

If we add certain dyes, such as aniline-blue or congo-reil, to the 
water in contact with the protoplasm of a cell, we notice that it does 
not enter ; the cell remains unstained. That this is not due to an 
obstruction anywhere but on the surface is shown by the fact 
observed by Kite (1913) that, if introduced by a capillary tube into 
the interior of a cell, congo-red freely and rapidly diffuses throughout 
the contents. Now it was observed by Nageli (185a), and confirmed 
by Pfeffer (1890) and others, that if a mass of protoplasm be broken 



124 REPORTS (IN THE STATE OF SCIENCE. .1918. 

up into several smaller pieces, these parts when free assume a spher- 
ical shape, and form at once on their surfaces a layer with the 
same properties as regards permeability as the original protoplasmic 
membrane had. 

If the cell substance is in contact with a liquid containing various 
substances in solution, as in the tissues of the higher plants and 
animals and in the case of the vacuoles in the interior of the cell,, 
then the surface film will contain constituents of both phases and its 
properties will not be identical with those of a membrane formed in 
contact with water only. Evidence of this was found by Osterhout 
(1913). 

It is obvious that the properties of the cell membrane as regards 
permeability to solutes both in the external liquid and in the interior 
of the protoplasm must play an important part in the life of the cell. 
While it is impossible to deny that a film of some sort must be formed, 
it is held by some investigators that sufficient evidence does not exist 
that it is possessed of the property of semi-permeability, at all events 
as regards crystalloids (see especially Moore and Roaf, 11)08). If this 
be so, it is clear that the escape of such constituents from the cell 
must be prevented by their existence therein in fixed combination 
with solid parts. The evidence on this question must be examined. 

There is no doubt that the salts present inside a cell may differ, 
not only in concentration, but in their chemical nature, from those in 
the external liquid. Perhaps the most striking case is that of the red 
blood corpuscles of the rabbit. Abderhalden (189^, p. 100) found 
that the blood serum contains O'M per cent, uf sodium salts, while 
the corpuscles contain none at all ; whereas the corpuscles contain 
twenty times as much potassium salts as the serum does. Similar 
facts have been described in the case of the muscle cells. The 
behaviour towards acid and alkali is interesting. Neither hydro- 
chloric acid nor sodium hydroxide is capable of entrance into the 
uninjured cell. If jellyfish are allowed to swim in sea water to 
which neutral red has been added, they take up the dye into their 
cells, where it has the orange-red colour of the neutral solution. 
Bethe (1909) added hydrochloric acid until the colour of the dye in 
the water was changed to the cherry red of the acid solution. But 
the contents of the cells underwent no change in colour until enough 
acid had been added to stop the movements and kill the organisms. 
Warburg (1910) showed that the colour of neutral red inside the eggs 
of the sea urchin, which are acid, was unchanged by the addition of 
sodium hydroxide to the water, but immediatnly . changed to yellow 
by a small quantity of ammonia. 

But, it may be said, no evidence has been given that the electro- 
lytes inside the cell are free to diffuse, even if the membrane allowed 
them to pass. The fact that the osmotic pressure inside cells is too 
great to be accounted for except by the presence of small molecules 
in the free state is indirect proof. Animal cells require, to prevent 
their swelling and rupture by osmosis, an external solution equivalent 
to 5"4 per cent, glucose or 0*9 per cent, sodium chloride ; that is, a 
solution of 0'3 molar concentration. The osmotic pressure of this is 
6'7 atmospheres. If we take a colloid which has as great an osmotic 
pressure as haemoglobin has, we find, on calculation, that a solution 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 125 

of the necessary molar concentration would be solid. Even congo- 
red would require to be 21 per cent., a value far exceeding its 
solubility in water. 

Hober (1910-1912) has shown, moreover, that there are free 
electrolytes present in cells. He made use of two methods. The 
first was by determining the increase in capacity of a condenser 
when a conductor is placed between its plates. Red blood corpuscles 
showed a conductivity about equal to that of deci-normal potassium 
chloride. The second method depends on the damping of the vibra- 
tion of a rapidly alternating current in a coil by the presence of a 
conductor in the axis of the coil. By this method . the blood 
corpuscles had the conductivity of a solution of potassium chloride 
between 0"1 and 0"4 per cent., muscle between 0"1 and (>2 per cent. 
Although the methods are probably not sufficiently sensitive to give 
exact measurements of the concentration, they show clearly that free 
electrolytes are actually present. 

Another experimental result pointing to the same conclusion may 
be referred to. When cells are immersed in dilute copper sulphate, 
alcohol, acetone or aniline, there is a marked increase in the 
conductivity of the outer solution, as shown by Stiles and .Jorgensen 
(1915 and 1917). The additional ions must have come from the 
interior of the cells. 

Living cells oppose an enormous resistance to the passage of an 
electrical current and if it were possible to examine them free from 
external electrolytes, it is probable that they would be found to be 
non-conductors in respect of currents applied by electrodes external 
to them. But, if they contain free electrolytes, it seems to the 
writer that the only satisfactory explanation of inability to conduct 
electrical currents is that the cell is surrounded by a membrane 
impermeable to these electrolytes, so that there is no possibility of 
their conveying charges from one electrode to the other. This 
phenomenon is shown in an interesting way in the method used by 
Morse (1914, p. 83) to prepare his copper ferrocyanide cells by 
electrolytic deposition. As the membrane becomes more perfect, the 
resistance goes up steadily and may amount, after soaking in water, 
to a million ohms. 

The cell membrane can be deprived of this property, of resistance 
to the passage of currents, by the action of heat, of aniesthetics and 
so on. After this treatment the cells conduct currents readily. 

We may conclude that, when examined under normal conditions 
and at rest, living cells are surrounded by a membrane impermeable 
to most salts, to strong acids and bases, and also, as shown by osmotic 
experiments, to glucose and to amino-acids. There are, however, 
certain crystalloids to which the cell appears to be permeable under 
all conditions. These are urea, ammonium hydroxide and some 
other ammonium salts, certain dyes of low molecular weight, 
alcohols, etc. But in some of these cases, it is not clear that n 3 damage 
has been done to the membrane by the solution applied, a difficulty 
not always taken into consideration. 

But the physiologist will raise an objection. If the membrane is 
impermeable to glucose and sodium chloride how does the cell ever 
obtain these materials for its active processes 'i The answer is to be 



126 HEPOETS OX THE STATE OF SCIENCE. 1918. 

obtained from the mode of production of the membrane. If it is 
composed of materials contained in the protoplasm of the cell it will 
naturally vary its nature according to the state of the cell, while, 
being a complex colloidal mixture, it will be easily accessible to the 
influence of electrolytes. But what actual evidence have we that it 
may become permeable to electrolytes under any conditions ? 

Direct proof of such changes under natural conditions is clearly 
difficult, but Lillie (1913) noticed that the cells of the larva of 
Arenkola when in a state of contraction lost their normal pigment, 
which is usually in solution in the cell contents. Garmus (1912) 
found that certain secreting cells becam^ less permeable to dyes 
under the influence of atropine, more permeable under pilocarpine. 
The point of these observations is that pilocarpine excites glands to 
activity ; atropine stops their activity. Indirect pi-oofs are more in 
number. The change of electrical conductivity already referred to is 
a convenient means of detecting changes of permeability. The egg 
cell on fertilization increases in conductivity (McClendon, 1910, 
Gray, 1916), as also does the muscle cell on contraction (McClendon, 
1912). The movements of the sensitive plant are usually ascribed to 
an increase of permeability of the cell membranes of the lower side 
of the "pulvinus." In this way the cells, which are normally 
distended owing to the osmotic pressure of certain solutes in their 
interior, lose these solutes and thus the distension due to their 
osmotic pressure. Blackman and Paine (J918), however, show that, 
although there is evidence of a very small escape of electrolytes, it is 
too small to account for the phenomenon, which can be repeated 
many times with the tissue immersed in warm water. They consider 
it more probable that the loss of turgor is due to a sudden decrease in 
concentration of osmotically active substances in the cell. 

The effects of certain agents on the cell, producing a temporary, 
reversible increase in permeability of the membrane, show how the 
necessary changes might be produced. The most instructive are 
those produced by inorganic salts. Ringer fl8tS2) was the first to 
show that the frog's heart is incapable of continued activity in a pure 
solution of sodium chloride, even of the correct osmotic concentration, 
whereas the addition of salts of calcium and of potassium in relatively 
small amount enabled the beats to continue indefinitely. A large 
number of experiments on such "balanced solutions" were made by 
Loeb (1901 and onwards) and brought into relation with changes 
in the j^ermeability of the cell membrane. The experiments of 
Osterhont (1911) on the seaweed. Laminaria, sjiowed that the tissue 
increased greatly in electrical conductivity when immersed in a solution 
equivalent to sea water, but containing sodium chloride only, returning 
to its normal state on the addition of a certain proportion of calcium 
chloride. No permanent damage was done to the cells (Osterhout, 
1915) by repeating the experiment many times. The explanation 
given by the investigator himself is not quite clear, but to the present 
writer it seems to be as follows : As we saw above, the cells in 
normal conditions are non-conductors because their surface mem- 
branes do not permit the passage of ions. Under the influence of 
sodium ions these membranes become permeable and allow free 
movement of ions carrying electric charges through them. Calcium 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAT, APPLICATIONS. 127 

ions restore the normal state of semi-permeabilitj . In this connec- 
tion, the experiments of Clowes (11)16), referred to in the preceding 
section, are significant. We have seen that the constituents of the 
cell membrane are most probably fatty substances, since they lower 
surface tension, together with concentrated solutions of emulsoid 
colloids in watei-, perhaps in the gel state, but certainly forming a 
watery phase. In other words, we have a system similar to that of 
oil and water in the experiments of Clowes, but more complex. 
Undev the influence of sodium salts, Clowes' emulsion was one of oil 
drops in a continuous watery phase and therefore permeable to 
water and to solutes therein. On the other hand, under the influence 
of calcium salts, a phase reversal occurred, so that there was then an 
emulsion of water drops in a continuous oil phase. Such a system 
would be impermeable to water, but permeable to substances soluble 
in oil. A change of this latter kind, if complete, would not give us 
the properties which the normal cell membrane possesses. It would 
be impermeable to water, as well as to solutes in water. These 
solutes would not be able to manifest their osmotic pressure and the 
volume of the cell would not have any relation to the osmotic 
pressure of an external solution, as we find that it actually has. 
Incidentally, however, it appears from some experiments by Lillie 
(1917), on the changes of permeability in fertilized egg cells, that, 
under exceptional conditions, the production of a " waterproof " 
membrane may be possible. But what we have to explain is the 
change from a membrane permeable to salts, sugar, &c. to one im- 
permeable to them, while remaining permeable to water. It is clear 
that the " Clowes effect," as we may call it, must be only partially 
effected. The way in which Bancroft explains the mode in which it 
takes place is summarized by Clowes as follows : — " The soaps 
present in the system tend, as stated above, to concentrate at the 
interface between water and oil and to form a coherent film. Soaps 
of monovalent cations, being readily dispersed in water but not in 
oil, form a film or diaphragm which is wetted more readily by water 
than by oil, consequently the surface tension is lower on the water 
than on the oil side. Since the area of the inside face of a film 
surrounding a sphere is obviously smaller than that of the outside 
face, the film tends to curve so that it encloses globules of oil in 
water, in this inanner reducing the area of the side of higher surface 
tension to a minimum as compared with that of lower surface tension. 
On the other hand, a film composed of soaps of divalent or trivalent 
cations, being freely dispersed in oil but not in water, is wetted more 
readily by the oil than by the water, the surface tension is lower on 
the oil than on the water side, and the film tends to curve in such a 
manner as to enclose the globules of water in an outer or continuous 
oil phase." The process is dependent, on the presence of a film of 
soap between the phases and it is interesting to note the powerful 
effect of sodium oleate in destroying the membrane of the red blood 
corpuscles, while pure olein has not this effect. 

During the process of phase reversal, as described above, there is 
a stage in which one of the two phases is drawn out into elongated 
drops with narrow films or channels of tlie other phase between 
them. This is shown in Figure 2 of the paper by Clowes. Now, if 



128 REPORTS ON THE STATE OF SCIENCE. 1918. 

these pores were small enough, we have the possibility of the pro- 
duction of a membrane with the structure that Traube held that of 
the copper f errocyanide membrane to be, namely, a sieve whose holes 
were of dimensions such that water molecules could pass through, 
while larger molecules, such as those of calcium chloride or potas- 
sium suljjhate, could not. Here we meet with the disputed question 
of the nature of tlie semi-permeable membrane in general. It seems 
to the writer that the evidence in favour of Traube's original view 
is very strong, although further evidence on the point is much 
required. In the case of membranes such as those of parchment 
paper or collodion, which are permeable to water and the small 
molecules of crystalloids, impermeable to the large molecules or 
aggregates of colloids, the degree of permeability appears to be strictly 
in proportion to the dimensions of the particles of the solutes. In 
the case of the copper ferrocyanide membrane, some observers hold 
that the passage of water depends on the different degrees of hydra- 
tion of the colloid material of the membrane on its two faces. Even 
Morse (1914, p. 87) appears to hold this view, but the degree of 
hydration of colloids follows quite a different law from that of 
osmotic pressure. While the osmotic pressure of a solution is 
directly proportional to the molar concentration, not the chemical 
nature, of the solute, the hydration by salt solutions follows the 
series known as that of Hofmeister, where sodium and lithium salts, 
for example, behave differently from one another. Some inves- 
tigators, moreover, state that non-electrolytes have no influence on 
the amount of water taken up by colloids. Objection also may be 
made to the theory of the production of osmosis by surface tension 
effects. Surface tension is not a function of molar concentration 
only, whereas osmotic pressure is. But, however this may be, 
Tinker's (1916) photographs show a definitely porous structure in 
the copper ferrocyanide membrane. The measurements given by 
him of the dimensions of the pores must be received with caution, 
since the published photogi-aphs show obvious diffraction. Indeed, 
the method of illumination used, a narrow cone of light, is not in 
agreement with the recognised methods of " critical " illumination, 
with a wide angled cone, adopted by the microscopists. The con- 
clusions drawn as to adsorption of water molecules on the walls of the 
pores are also open to question. Further discussion of the problem 
is beyond the scope of this report, but we have seen how a sieve-like 
membrane might be formed on the surface of protoplasm, whereas a 
membrane which owed its semi-permeable character to its behaviour 
as a solvent for some solutes and not for others is much morS difficult 
to imagine. 

At this place a few words are desirable with respect to the Over- 
ton (1899) theory of the membrane as composed of lipoid matei-ial. 
It is a striking fact that the cell membrane is always permeable to 
those substances which are soluble in fats, such as the alcohols are. 
But, when we extend this statement and make it to apply generally, 
we meet with difficulties. For instance, certain dyes, such as 
methylene blue, are found to penetrate the cell membrane, while 
others, aniline blue, do not. Methylene blue is insoluble in chloro- 
form, but if a solution of kephalin (a lipoid allied to lecithin) in 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 129 

chloroform be shaken with a solution of methylene blue in water, 
the chloroform phase is found to be coloured blue. In order to 
understand what this really means, we must refer to the work of 
Loewe (1912). He shows that kephalin is not in true solution in 
chloroform, but in large colloidal aggregates, since no measurable 
change in the boiling point of chloroform is produced by dissolving 
kephalin in it. The second point brought out is that, when meth- 
leue blue is present m the two phases, water and lipoid-chloroform, 
in coatacc, if it were a case of true solution in the latter, there would 
be a definite " parti tion-coetiicient," independent of the absolute 
concentration. This is not the case. There is relatively less in the 
latter phase as the concentration rises, and the law followed is 
the parabolic law of adsorption. The actual ratio is such as to 
involve a high polymerization of the dye in both solvents, 
whereas electrical conductivity measurements indicate normal mole- 
cular weights in water. Again, if the dye were dissolved in the 
lipoid, a notable proportion of it would escape to water if placed 
in contact with it. Only a very minute amount leaves the lipoid. 
In fact, it behaves just like a negatively charged surfnce such as 
that of paper in water, to " basic " dyes, which are hydrolyzed in 
solution, and whose coloured base becomes a positively charged col- 
loidal particle. As Freundlich has pointed out, the adsorption in 
such cases is so great that equilibrium is only effected when a very 
small amount of the dye is left in the water. Further confirmation 
of the view that we have to deal with a surface condensation only is 
that, if a mass of kephalin be placed in contact with a solution of 
methylene blue in water, the dye does not pass into the lipoid. 
Similar evidence was obtained in the cases of other " lipoid-soluble " 
substances, such as the alkaloids and certain narcotics. It is impos- 
sible to accept the view that the cell membrane is a lipoid film, and 
that the passage of substances into and out of the protoplasm depends 
on their solubility in lipoids. 

It is also easy to show that a membrane of pure protein, as held 
by some, has not the requisite properties. Nothing but a complex 
system of more than one phase will suffice to explain the changes 
in permeability which are shown by the surface membrane of the cell. 

We have already spoken of the effect of certain electrolytes on 
the membrane. Further discussion as to the meaning of " balanced" 
action will be found in the following section of this report. A few 
more facts in connection with permeability may be given here. 
Newton Harvey (1911) was unable to find any geneial law as to the 
relation of cells to acids, except that if an acid is soluble in lipoids it 
penetrates freely ; if not, the cell surface must be changed before it 
can enter. Strong bases do not enter ; weak bases do. This fact 
suggests that the permeability is in respect of one ion only. Since 
weak bases enter, OH' ions must do so. Therefore, when sodium 
hydroxide does not, it must be that the sodium ion is obstructed. 
This point was indicated by Ostwald (1890). It is sufficient for a 
membrane to be impermeable to one of the oppositely charged ions 
of an electrolytically dissociated solute in order that the solute may 
be completely kept out. The reason is because the two ions cannot 
be separated without the expenditure of a large amount of energy 

20895 E 



130 REPORTS ON THE STATE OF SCIENCE. 1918. 

on account of electrostatic forces. We shall see presently that this 
fact plays an important part in the electrical behaviour of living 
cells. 

The action of anccsthetics is of interest. Osterhout (1916) has 
shown that there are two stages in this action, of opposite nature. 
The first one is a decrease in permeability, the second an increase. 
The former is rt-covered from on removal of the anaesthetic, while the 
latter is a toxic effect, irreversible and leading to death. Remember- 
ing that the characteristic action of anaesthetics is to 'make a cell 
unable to enter into a state of excitation, and that the state of ex- 
citation is associated with an increase of permeability, we see that 
the first stage is the real anaesthetic action. Whether the state of 
excitation is a consequence of the permeability change, or vice versa, 
is not certain, but it may well be that the prevention of the per- 
meability change also removes the possibility of excitation. The 
pronounced "lipoid-solubility " of the volatile anaesthetics suggests 
that their action is on the lipoid constituents of the membrane, but 
magnesium salts have a similar action, so that it seems probable that 
the relationship to lipoids may be merely incidental. 

The interesting observations of Meigs (1915) on the permeability 
of membranes of colloidal calcium and magnesium phosphates show 
that such membranes may be impermeable to sugar, phosphates, &c., 
but highly permeable to ethyl alcohol. Hence this latter property is 
not limited to " lipoid " membranes. 

As pointed out previously, calcium salts decrease, while sodium 
salts increase the permeability of the cell-membrane, so that the effects 
may be balanced. Anaesthetics also decrease the permeability. 
Hence they should oppose the effect of sodium salts. This has been 
shown by Lillie (1914) to be the case. 

Since the membrane is a local concentration of components of 
the protoplasm of the cell, there must always be an equilibrium 
between the two. Hence a change in either involves a change in 
both. It is not a matter of surprise, therefore, to find that substances 
applied to the outside of a cell may effect marked changes in its 
chemical behaviour, even when they are unable to pass through the 
membrane. Thus, as mentioned above, sodium hydroxide does not 
enter the living cell, but it increases greatly the rate of its oxidation 
processes. Newton Harvey (1914, p. 142) finds that although weak 
alkalies (ammonia and amines) enter muscle cells almost instantly, 
as shown by the change in colour of neutral red within the cells, 
their contraction does not cease until some time later. Strong 
alkalies (sodium hydroxide^ abolish contractile power at once, but 
do not enter the cell until long afterwards. The effect of electrolytes 
on the beat of the heart and on muscular contraction in general is 
on the cell membrane (see Straub, 1912, p. 14, and Overton, 1904, 
p. 202). A somewhat remarkable phenomenon occurs in the case 
of such drugs as muscarine and pilocarpine, which produce their 
effects while passing through the membrane in either direction, 
whether entering or leaving the cell. When in equal concentration 
on both sides their effect is nil (Straub, 1907, Neukirch, 1912). 

In order that the cells of the tissues of the higher animals shall 
maintain their normal water content and volume, it is necessary that 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 131 

they be surrounded by a solution of the same osmotic pressure as 
their own contents. The fact that whatever be the chemical nature 
of the solute, so long as it does not injure the cell, its osmotic pres- 
sure must be of the same definite value, unless either swelling or 
contraction of the cell is to occur, is in itself proof of the semi- 
permeability of the cell membrane. The facts are so simply ex- 
plained on this view that it is somewhat puzzling to understand why 
elaborate theories should be invented to explain the phenomena 
otherwise. The question naturally arises, nevertheless, how do 
organisms like amoeba, living in water, avoid swelling up and 
disintegration on account of the osmotic pressure of their contents ? 
We have no accurate knowledge of the value of this osmotic pressure, 
but we know that it must be higher than that of the extremely 
dilute solution in which they live. It is pointed out by Stempell 
(1914) that the well-known 2^H'isaiing vacuole of protozoa is the 
means of removing excess of water taken in by osmosis. A minute 
drop of water makes its appearance at a particular place in the 
protoplasm, gradually increases in size until it touches the outer 
surface of the organism and bursts to the exterior. The process is 
continually repeated. 

The taking, up of solid particles and small organisms, such as 
alga? and bacteria, by living cells, as in the process of ' phagocytosis,' 
seems at first sight to be difficult to understand. If molecules of 
sodium chloride are unable to pass through, how do such large 
masses manage to do so ? The writer has suggested in another 
place (' General Physiology,' p. 144) that the membrane is actually 
perforated in the latter process, as when a needle is dropped through 
a soap film, the film closing up again as the object passes through. 
As we have seen, the cell-membrane is not a fixed structure, and the 
difference between the impermeability to salts and the permeability 
to large particles is that in the former case the molecules would 
have to pass through pores which are too small for them ; in the 
latter case they break the film mechanically, but it is formed again 
behind them. 

It will be of some interest, in conclusion, to refer briefly to some 
typical physiological phenomena in which membranes of variable 
permeability are believed to play an essential part. A limited 
selection is all that is possible, since, as pointed out above, the 
properties intervene in nearly all vital processes. 

I. The Stimulation of Nerve. Nernst (1899) was the first to 
suggest that the electrical stimulation of nerves is conditioned by the 
concentration of ions of a certain sign of charge in the neighbourhood 
of a semi-permeable membrane. He made no statement as to the 
situation of such a membrane, nor did he claim that his theory was 
more than an approximation. A more complete extension of this 
theory was made by A. V. Hill (1910) and found by Keith Lucas 
(1910) to satisfy experimental results. There is no evidence of the 
existence of membranes within the nerve fibre itself, the contents of 
which, so far as can be made out, are liquid. Hence the membrane 
in question must be that on the exterior of the central core, that is, 
the cell-membrane. The relation of increased permeability to the 
condition of excitation has been emphasized by Li Hie (1914) and the 

20895 , E 5} 



132 HEPORTS ON THE STATE OF SCIENCE. 1918. 

manner in which it is possible to explain the conduction along a 
nerve fibre on the basis of the disappearance of the electrical charge 
described below is explained (li<15). 

II. Electromotive Phenomena. If a membrane is permeable to 
ions of one sign only, a Helmholtz double layer is established, such 
that the opposite sides of the membrane obtain opposite chaiges, 
owing to the ions held there. In other words, the membrane is 
polarized. It has been known for many years that muscle and nerve 
fibres show, on testing, that their outer surfaces have a positive 
charge. This can be most satisfactorily accounted for on the hypo- 
thesis that the cell-membrane is impermeable to certain anions, 
permeable to the corresponding cations. In the address to the 
Physiology Section of the British Association in 1915, I showed how 
this view explains the phenomena met with and may venture to 
repeat the paragraph here : — 

'' Suppose that we lead off, tr> some instrument capable of detecting 
differences of electrical potential, two places on the outer surface of 
a cell having the propei'ties referred to. It will be clear that we shall 
obtain no indication of the presence of the electrical charge, because 
the two points are equipotential and we cannot get at the interior of 
the cell without destroying its structure. But if excitation means in- 
creased permeability, the double layer will disappear at an excited spot, 
owing to indiscriminate mixing of both kinds of ions, and we are then 
practically leading off from the interior of the cell, that is, from the 
internal component of the double layer,while the unexcited spot is still 
led off from the outer component. The two contacts are no longer 
equipotential. Since we find experimentally that a point at rest is 
electrically positive to an excited one, the outer component must be 
positive, or the membrane is permeable to certain cations, impermeable 
to the corresponding anions. Any action on the cell such as would 
make tha membrane permeable-injury — certain chemical agents and 
so on — would have the same effect as the state of excitation." The 
jDoint of view taken here is practically identical with that of 
Bernstein (1913). Loeb (1915) has brought some objections to this 
view, based mainly on the fact that the application of salts to one of 
the places led off results in a change of the potential difference of 
such magnitude as to follow the well-known Nernst formula for 
concentration cells. I may point out that I have been able to show, 
both experimentally and by calculation (1911 and ' General Physio- 
logy,' pp. 648-650), that one can imitate the muscle cell by means of 
an osmometer, closed by a parchment paper membrane and filled with 
a solution of congo-red. This membrane is permeable to the sodium 
ions resulting from the electrolytic dissociation of the dye, but im- 
permeable to the anions. The only difference is in the sign of the 
charge on the inside and outside, the latter being negative in this 
case. The potential difference between the two sides, which can be 
modified or abolished by the addition to the outer liquid of a solute 
giving sodium or other cations, is found to be in accordance with the 
Nernst formula. In fact, a cell of the kind described is a model of 
the rationale of the electrode potential of the concentration battery. 
It seems that there is then no real opposition between the results 
obtained by Loeb and Beutner (1912) and the hypothesis advocated 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 133 

here. The potential difference between two liquid phases, referred 
to by Loeb, has clearly the same origin as the membrane potential of 
the cell. The former has been investigated by Haber and Klemen- 
siewicz (1909) in a well-known paper. If the salt is hydrolytically, 
as well as electrolytically, dissociated, a more complex state of affairs 
exists, which has been investigated thermodynamically by Donnan 
(1911). If, for example, we are dealing with a sodium salt of a 
weak acid, there are no forces to restrain the free diffusion of sodium 
hydroxide throiigh the membrane, so that the alkali would be 
detected on the outer side, while the colloidal acid inside might be 
precipitated. Moreover, when no hydrolysis is present, if an acid, 
even as weak as carbonic, is present outside, the sodium ions at the 
membrane are partially replaced by hydrogen ions, the sodium com- 
bines to form carbonate and. by renewal of the outer fluid, all of the 
sodium can in time be removed. 

III. Secretion. Although it Is clear that complex changes of 
permeability occur in this process, too little definite knowledge is at 
hand to make detailed discussion of profit. The reader may be 
referred to my "General Physiology," pp. 163 and 334, for a brief 
statement. The point of immediate interest is that, suppose we have 
an inverted U-tube with a semi-permeable membrane at both ends 
and filled with a solution of cane sugar. If we immerse both ends 
in water in two separate vessels, a large osmotic pressure will develop 
inside the tube, but no liquid will escape, provided that the mem- 
branes can withstand the pressure. Now imagine the semi-permeable 
membrane at one end to become permeable to the sugar. A current 
of water, carrying sugar in solution, will pass through the tube from 
one vessel to the other, as long as there is any sugar left in the tube. 
This tube may be compared to the cells of a secreting gland, one end 
being in contact with lymph, filtered from the blood, the other end 
with the watery secretion in the duct. Water can be conveyed in 
the way described by a change in the permeability of the end 
bordering on the duct. Cases of this kind have been described by 
Lepeschkin (1906) in plant mechanisms. 

IV. The Bloodvessels. Scott (1916) showed that when liquid is 
absorbed into the blood from the tissue spaces, this liquid, while 
containing all the crystalloids, is free from the colloids. The walls 
of the blood vessels are therefore impermeable to colloids. If, then, 
these colloids are such as have an osmotic pressure, the conditions 
are such that it can be manifested and it will play an important part 
in the passage of water from the blood to the tissues, and vice versa. 

A few words are necessary therefore on the osmotic pressure of 
colloids. Starling (1896) showed that those present in the blood 
have an osmotic pressure of about 30 to 40 mm. of mercury at room 
temperature. Later work by Moore and Roaf (19')7), Donnan and 
Harris (1911), Sorensen (1918) and myself (1911) showed that there 
are many colloids whose active elements are sufficiently small to give 
a fairly high osmotic pressure. When the colloid is an electrolytically 
dissociated salt of a diffusible ion with one to which the membrane 
is impermeable, as in the case of congo-red with a parchment paper 
membrane, an interesting question arises, whether the diffusible ions, 
which are held only by electrostatic forces, play their part in the 

20895 E 3 



134 REPORTS ON THE STATE OF SCIENCE. 1918. 

osmotic pressure. I showed (1911), by determinations of the osmotic 
pressure of congo-red solutions by a vapour pressure method, that 
the values were the same as those given by the parchment paper 
membrane. Therefore, all the elements present in the solution, 
including the sodium ions, gave their proper contribution to the 
osmotic pressure measured by the osmometer method ; otherwise, the 
vapour pressure measurements would have been much higher than 
those with the latter method. Theoretical considerations and cal- 
culations based on them (Bayliss, "General Physiology," p. 649) 
confirm the fact. Owing to the osmotic activity of all the ions 
formed by an electrolytically dissociated colloid comparatively high 
osmotic pressures may be manifested. This is the cause of the 
large rise in osmotic pressure produced by the addition of sodium 
hydroxide to a protein solution. 

In order that we may realize how the osmotic pressure of colloids 
is of importance in problems of the circulation of the blood it is 
necessary to remember that the pressure in the arteries is something 
over 100 mm. of mercury, falling regularly to about 8 mm. in the 
capillaries, and to zero in the small veins. Since the osmotic pressure 
of the colloids in the blood is only 40 mm. of mercury, and the walls 
of the blood vessels are freely permeable to water and crystalloids, it 
is clear that the osmotic pressure of the colloids, which tends to draw 
water in, is overpowered as far as the commencement of the 
capillaries. Thus a filtration outwards of blood, minus its colloids, 
takes place in that part of the vascular system in which the pressure 
exceeds 40 mm. The same process occurs in a part of the kidney, 
resulting in the production of what is a very dilute urine, being the 
first stage in the complete process. The blood then is continually 
losing liquid to the tissues up to a certain region in its course. But, 
as we follow the gradual fall in the blood pressure along the 
capillaries, we come to a point where the osmotic pressure of the 
colloids, which has risen somewhat owing to the loss of water, is 
higher than the blood pressure. From this point onwards water is 
taken in again from the tissue spaces by osmosis. This latter process, 
however, does not usually suffice to balance the loss completely, and 
the difference is carried away by the lymphatic channels, and finally 
returned to the blood by the thoracic duct. Consider next what 
will happen when a dilute salt solution is introduced into the veins 
in order to replace blood which has been lost by escape from injured 
blood vessels for example. It is clear that the concentration of 
colloids in the blood is lowered, and therefore their osmotic pressure. 
The result is that more rapid loss of liquid by filtration occurs, while 
the region travelled before the blood pressure falls sufficiently to 
permit osmotic inflow is lengthened, leaving a less distance in which 
reabsorption takes place. The net effect is that much more liquid 
escapes to the tissues, while the blood quickly loses that which has 
been put in. In practice this is found to be the case. Simple saline 
solutions are useless. The present writer has shown (1916), however, 
that if a colloid, such as gelatin, or better, gum acacia, be added in 
such amount to the solution injected as to raise its colloidal osmotic 
pressure to that of the blood, then it remains in the .blood vessels 
raising the blood pressure and forming an effective substitute for the 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 135 

/ 

blood lost. Indeed, a gum solution of this kind was in extensive 
use during the war. 

BlBLIOQRAPHT. 

Abdeehalden, Emil. (1898), ' Zeitschr. physiol. Chem.' 25, 65. 

' Zur quantitative vergleich. Analyse des Blutes.' 
Bayliss, W. M. (1911), 'Proc. Roy. Soc.', B. 84, 229. 

' The 0!<motic Pressure cf Electrolytically Dissoc-iated Colloids.' 
Batliss, W. M. (1916), 'Proc. Roy. Soc.', B. 89, 380. 

' Methods of Raising a Low Arterial Pressure.' 
Bernstein, Julius (1913), ' Biochem. Zeitschr.', 50, 39:5. 

' Zur elektrocheinischen Grundlage der bioelektrischea Potentiale.' 
Bethe, a. (1909), ' Pfluger's Archiv.', 127, 219. 

'Die Bedeutung der Elektrolyten ftir die rhythmischen Bewegungen der 
Medusen. II. Angritfspunkt der Salze, Einfluss der Anionen, Oil und H lonen.' 
Chambers, Rob., Jr. (1917), ' Amer. Journ. Physiol.' 43, 1. 

' Microdissection Studies. I. The Visible Structure of Cell Protoplasm and 
Death Changes.' 
Clowes, G. H. A. (1916), 'Journ. Physic. Chem.', 20, ^07. 

' Protoplasmic Equilibrium. Action of Antagonistic Electrolytes on Emulsions 
and Living Cells.' 
DONNAH, F. G. (1911), 'Zeitschr. Elektrochem.', 17, .572. 

' Theorie der Membrangleichgewichte und Membranpotentiale bei Vorhandensein 
von nicht dialysierenden Elektrolyten.' 
DONNAN, F. G., and Harris, A. B. (1911), ' Trans. Chem. Soc.', 99, 1554. 

' The Osmotic Pressure and Conductivity of Aqueous Solutions of Congo-red, 
and Reversible Membrane Equilibria.' 
Freundliuh, Herbert (1909). 

' Kapillarchemie,' Leipzig. 591pp. 
Garmus, a. (1912). ' Zeitschr. Biol.', 58, 185. 

' Die Permeabilitat der Driisenzellen f iir FarbstoflFe.' 
Gray, James (1916), ' Phil. Trans. Roy. Soc.', 207 B-, 481. 

' The Electrical Conductivity of Echinoderm Eggs anc its Bearing on the 
Problems of Fertilisation and Artificial Parthenogenesis.' 
Haber, F., and Z. Klemensievvicz (1909), 'Zeitschr. physik. Chem.', 67i 385. 

' Ueber elektrische Phasengrenzkrafte.' 
Harvey, E. Newton (1914). 'Internat. Zeitschr. physik-chem. Biologie,' 1, 463. 

' The permeability of cells for acids.' 

'Publications of the Carnegie Institution of Washington,' No. 183, 131. 

'The Relation between the Rate of Penetration of Marine Tissues by Alkali and 
the Change in Functional Activity Induced by the Alkali.' 
Hill, A. V. (1910), ' Journ. PhysioL', 40, 190. 

' A New Mathematical Treatment of Changes of Ionic Concentration in Muscle 
and Nerve under the Action of Electric Currents, with a Theory as to their Mode of 
Excitation.' 
Hoeber, R. (1912), ' Pfliiger's Archiv.', 148, 189. 

'Ein zweites Verfahren, die Leitfiihigkeit im Inneren der Zellen zu messen.' 
Hoeber, R. (1913), ' Pfliiger's Archiv.', 150, 15. 

' Messungen der inneren Leitfiihigkeit von Zellen.' 
Kite, G. L. (1913), 'Biolog. Bulletin,' 25- 

'The Relative Permeability of the Surface and Interior Portions of the Cytoplasm 
of Animal and Plant Cells.' 
Lepeschkin, W. W. (1906), ' Beiheft z. Botan. Cbl.', 19, i, 409. 

' Beitrage zur Kenntnis der Mechanismus der aktiven VVasserausscheidung.' 
LiLLiE, Ralph S. (1913), 'Science,' 37, 764. 

' The Physico-chemical Conditions of Anaesthetic Action. Correlation between 
the Anti-stimulating and the Anti-cytolytic Action of Anesthetics.' 
LiLLiE, Ralph S. (1914), ' Popular Science Monthly,' June, 1914, p. 579. 

' The General Physico-chemical Conditions of Stimulation in Living Organisms.' 
LiLLiE, Ralph S. (1914), 'Journ. Exper. Zool.', 16, 591. 

' Antagonism between Salts and Anie^thetics.' 
LiLLiE, Ralph S (1915), ' Aratr. Journ. Physiol.', 37i 348. 

' The Conditions of Conduction of Excitaticu iu Irritable Cells and Tissues and 
especially in Nerve.' 

20895 E 4 



136 REPORTS ON THE STATE OF SCIENCE. 1918. 

LiLLiE. Ealph S. (1917), ' Amer. Journ. Physiol.', 43i 43. 

' The Conditions Determining the Rate of Entrance ot Water into Fertilized and 
Unfertilized Arbacia Eggs, and the Geueral Relation of Changes of Permeability to 
Activation.' 
LoEB, Jacques (1901), 'Pfliifrer's Archiv.', 88- 68. 

'Ueber den Einfluss der Werthigkeit uad moglicher Weise der elektrischen 
Ladling von lonen auf ihre antitoxische Wirkung.' 
LoEB, Jacques (1915), 'Proc. Nat. Acad. Sci., Washington,' 1, 473. 

' The Mechanism of Antagonistic Salt Action.' 
LoEB. Jacques (19 i 5), ' Science,' 481 643. 

' Electromotive Phenomena and Membrane Permeability.' 
LoEB, Jacques, and R. Beitneb (1912), 'Biochem. Zeitschr.' 41, 308. 

'Ueher die Potentialdifferenzen an der unversehrten und verletzten Oberflache 
pflanzlicher imd tierische Oigane.' 
LOEWE, S. (1912), Biochem. Zeitchr.'. 42. 150-218. 

'Zur physikalishe Chemie der Lipoide.' 
Lucas, Kei ih (1906), ■ Journ. Physiol.' 35, 103. 

' On the Optimal Electric Stimuli of Muscle and Nerve.' 
McCi.END-iN. J. F. (1910), ' Amer. Journ. Physiol.', 27, 240. 
'On the Dynamics of Cell Division.' 
(Increase of permeability on fertilization.) 
McClend. N, J. F. (191-1), ' Amer. Journ. Physiol.' 29, 302. 

' The Increased Permeability of Striiited Vluscle to Ions during Contraction.' 
Meigs, E B. (1915), ' Amer. Journ. Phy.-<iol.' 38, 456. 

' The Osmotic Properties of Calcium and Magnesium Phosphates in Relation to 
those of Living Cells.' 
Moore, B.. and H. E. Roaf (1907), ' Biochem. Journ.' 2. 34. 

' Direct Measurements of the Osmotic Properties of Certain Colloids.' 
Moore, B., and H. B. Roaf (1908), • Biochem. Journ.' 3, 55. 

' On the Equilibrium betvreen the Cell and its Environment in regard to Soluble 
Constituents, with especial reference to the GBmotic Equilibrium of the Red Blood 
Corpuscle.' 
Morse, H. N. (1914), ' Carnegie Institution of Washington,' Publication No. 198. 

' The Osmotic Pressure of Aqueous Solutions.' 
Naegeli, Carl von (1885), ' Pflanzenphysiol. Studien,' 1, 1. 

' Primordial Schlauch.' 
Nernst. W. (1899), 'Gottingen Nachrichten. Math. Phys. Kl. (1899), 104. 

' Zur Theorie der elektrischen Reizung.' 
OSTERHOUT, W. J. V. (1911), ' Science,' 34, 187. 

' Permeability of Living Cells to Salts in Pure and in Balanced Solutions.' 
OsTERHOUT, W. J. V. (1913), ' Science,' 38- 408. 

' The Organization of the Cell vrith Respect to Permeability.' 
OsTERHOUT, W. J. V. (1915). 'Botan. Gazette.' 59, 242. 

'Extreme Alterations of Permeability without Injury.' 
OSTERHOUT, W. J. V. (1916), ' Botan. Gazette,' 61, 14«. 

' The Decrease of Permeability Produced by Anesthetics.' 
OSTWALD, W. (1890), 'Zeitschr. physik. Chem.' 6, 71. 

' Elektrische Eigenschalten halbdurchliissiger Scheidewande.' 
Overton, E. (1896), Jahrb. wiss. Botan.' 34, 669. 

' Studien iiber die Aufnahme der Anilinfarben durchdie lebende Zelle.' 
Overton, E. (1904), ' Pfliiger's Archiv,' 105, 176. 

' Studien iiber die Wirkung der Alkali- und Erdalkalisalze auf Skelettmuskeln 
und Nerven.' 

Pfeffer. W. (1890), ' Abh. Sachs. Ges. Wiss.', 16, 187. 
'Zur Kenntnis der Plasmahaut und der Vacuolen.' 
Ramsden, W. (1904), 'Proc. Roy. Soc.', 72, 156. 

' Separation of Solids in Surface Layers of Solutions and Suspensions.' 
Ringer, Sydney (1880), 'Journ. Physiol.', 3, 380. 

' Concerning the Influence exerted by each of the Constituents of the Blood on 
the Contraction of the Ventricle.' 
Scott. F. H. (1916), ' Journ. Physiol.' 50, 157. 

' The Mechanism of Fluid Absorption from Tissue Spaces.' 
SoRENSEN, S. p. L. (1918), ' Comptes rendus, Laboratoire de Carlsberg,' 12, 372 pp. 
'Studies on Proteins.' 
(Osmotic pressure of proteins on p. 262.) 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 137 

Starling, E. H. (1896), ' Journ. Physiol.', 19, 312. 

On the Absorption of Fluids from the Connective Tissue Spaces.' 

(Osmotic Pressure of Blood Colloids.) 
Stempell, W. (1914), 'Zool. Jahrb., Abt. allg. Zool. und Physiol, der Tiere,' 34 
iii., 437. 

' Ueber die Funktioa der pulsierendea Vakuole.' 
Stiles, W., and (. Joroensen (1917), 'Annals of l5otany,' 31, 47. 

' Studies in Permeability, iv. The action of various Organic Substances on the 
Permeability of the Plant Cell and its bearing on Czapek's Theory 0/ the Plasma 
Membrane.' 
Straiib. W. (1907), ' Pfluger's Archiv.' 119, 127. 

' Zur chemischen Kinetik der Muscarinwirkung.' 
Tinker, F. (1916), ' Proc. Roy. Soc.', 92 A-, 357. 

' The Microscopic Structure of Semipermeable Membranes and the part played b' 
Surface Forces in Osmosis.' 
Warburg, Otto (1910). 'Zeitschr.physlol. Chem.', 66- 305. 

' Oxydationen in lebenden Zellen nach Versuchen am Seeigelei.' 

(Impermeability to sodium hydroxide.) 

///. The Relation of Biochemical Colloids to Electrolytes. 

We have already met with several instances in which the inter- 
action between colloids and electrolytes plays an important part. In 
the present section, further analysis of such phenomena will be 
attempted. 

It is necessary to take account of the fact that the greater number 
of the colloids occurring in living organisms are proteins. These, 
being conjugated amino-acids, behave as amphoteric electrolytes, able 
to combine with strong acids by their 1^112 groups and with strong 
bases by their carboxyl groups. Electrolytically dissociated salts are 
thus formed, the protein ion being the cation in the former case, the 
anion in the latter. Although there is no doubt of this fact, it is 
sometimes forgotten that the protein itself is present in solution in 
the form of an anhydride, the NH2 and COOH groups are not free to 
combine with ions until hydrolyzed by the action of strong acids or 
bases. Nevertheless, various statements have been made to the effect 
that not only are chemical compounds formed with weak acids, but 
even with neutral salts. That this is not so is shown clearly by the 
results of Bugarsky and Liebermann (1898), who found no change in 
the freezing point on adding egg albumin to sodium chloride, 
whereas there was a marked depression with hydrochloric acid or 
sodium hydroxide. The evidence brought by Pfeiffier and ModeLski 
(1912), to the effect that amino-acids form definite chemical com- 
pounds with calcium and lithium chlorides and other salts, is not 
convincing and the present writer was unable to confirm their 
statements. 

Hardy (1905-6) finds that globulins form non-ionized complexes 
with neutral salts. On the other hand, Loeb (1918) holds that 
neutral salts with a univalent cation form highly ionizable salts 
with gelatin. The evidence is that powdered gelatin, after washing 
with m/8 or m/4 solution of sodium chloride, shows a further 
sv/elling when afterwards put ii? contact with a more dilute solution 
of a neutral salt with a univalent metal. There is a critical concen- 
tration above which this additional swelling is absent. And this 
concentration is half as great if the anion is bivalent, regardless of 
the nature of the anion and cation. The evidence is somewhat 



138 EEPORTS ON THE STATE OF SCIENCE. 1918. 

indirect, but it indicates an electrical effect independent of the 
chemical nature of the ion. Whether the conclusion is justilied that 
it implies the production of a definite salt seems doubtful. The 
difference between the osmotic pressures of equimolar solutions of 
sodium salts with uni-and bivalent anions must not be forgotten. 
A further difficulty is presented by the fact that calcium salts were 
not found to form ionizable compounds, whereas in the experiments 
of Pfeiflfer and Modelski (1912), the "compounds" of amino-acids 
■with calcium chloride were some of the easiest to prepare. If the 
contrast is due to the colloidal nature of gelatin, it is an additional 
reason to doubt the adequacy of explanation on pure electro-chemical 
lines. Why does Loeb speak of proteins as " so-called colloids " ? 

If a salt of a protein with a strong base or strong acid is exposed 
to an electric field between electrodes, the colloidal ion is deposited 
at one pole or the other according to whether it is anion or cation 
and the protein is naturally said to have a charge of the sign opposite 
to that of the pole at which it is deposited. But the sign of the 
charge on such a surface as that of paper can be changed by electro- 
lytes, even by weak acids and by neutral salts. In such cases, it 
seems that something other than actual salt formation must be the 
cause. Whatever may be the way in which the electric charge on 
the surface of insoluble particles or colloids is produced, whether by 
electrolytic dissociation at the surface, one ion being insoluble and 
fixed (see Hardy, 1910), or by other causes more allied to the 
phenomena of static electricity (Lewis, 1909), as appears to be the 
case with drops of petroleum in water, it is clear that the surface 
energy due to this charge would be reduced if ions of the opposite 
sign were deposited on it. The second law of therm -)dynamics 
would allow us to predict this fact, which has been called " electrical 
adsorption." It is shown in a striking way by the opposite effect of 
bivalent ions on the adsorption of colloidal dye ions by paper, when 
these have a different sign of charge. Some data on this point will 
be found in a paper by myself (1906). I was inclined to attribute the 
effect to a reversal in sign of the charge on the colloidal particles, but 
it is more satisfactorily explained as exerted on the paper. While, 
however, it is comparatively easy to see why the charge should 
be reduced to zero, it is not quite so easy to see why it should be 
replaced by a charge of the opposite sign, as Perrin, (1904, 1905), 
Mines (1912) and others have shown to be the case. Freandlich 
(1909, p. 245) has suggested that certain ions may be adsorbed in the 
mechanical way to a much greater extent than certain others with an 
opposite charge. The result would be a deposition on the surface in 
amount greater than merely necessary to neutralize the existing 
charge and sufficient to confer a charge of the opposite sign. (See 
especially the experiments of Freundlich and Schucht, 1913, and of 
Ishizaka, 1913.) 

We have, then, in addition to the chemical compounds of certain 
amphoteric electrolytes with strong acids and bases, as association of 
electrolytes with the surfaces of colloids in general, a relationship 
which appears to be of the nature|of adsorption. This is indicated by 
the law which expresses the proportion of electrolyte held by the 
colloid to that in the external phase. The law is expressed by the 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. Vid 

equation to one of the higher orders of parabolas. This is tlie reason 
why it is so ditiicult to remove, by repeated changes of water or 
dialysis, the last traces of electrolytes attached to colloids or coarsely 
heterogeneous systems. 

This difficulty of removing all electrolytes and other crystalloids 
from a colloidal solution has led some workers in the past to the 
belief that the osmotic pressure shown by some of these solutions 
was due to the electrolytes present. There are several reasons, theo- 
retical and experimental, that make this view inadmissible. In many 
cases, such as gelatin and congo-red, the more effectively these 
impurities are removed, the higher is the osmotic pressure. If the 
crystalloid is in any form of combination with the colloidal particle, 
chemical or by adsorption, it forms one indivisible system with it, so 
that if a colloidal particle is too large to possess the kinetic energy 
requisite to give an osmotic pressure, it would be even less able to do 
so if attached to another molecule. In fact, the association of a 
colloidal particle with an electrolyte would decrease the osmotic 
pressure given by it. If, on the other hand, the electrolytes are free, 
they must be removed by repeated dialysis. The osmotic pressure of 
haemoglobin (Hufner and Gansser, 1907) is that which it should have 
in accordance with its molecular weight as determined by chemical 
analysis. It is true that certain colloids, such as ferric hydroxide, 
become unstable if the last traces of ferric chloride are removed, but 
the particle consists of a complex of a variable number of ferric 
hydroxide molecules in adsorption with one or more ferric chloride 
molecules. The latter are not free. 

The greater number of the colloids of biochemical interest belong 
to the class called emulsoids. Their characteristic is that the two 
phases are not solid and liquid, but both contain solvent in different 
amounts. The two phases in tJiese biochemical colloids may be 
described as being, on the one hand, a solution of a small amount of 
the solvent in the solid, and, on the other hand, a dilate solution of 
the solid in the solvent. They may also be regarded as being both 
liquid, one of them possessed of a very high degree of viscosity. 
Such systems would not show a high surface tension at the interface, 
nor a high electrical charge. They are, accordingly, relatively to the 
suspensoid class, somewhat insensitive to the precipitating action of 
ions. At the same time, as Mines has shown (l'JI2, p. 211), the 
difference is not a fundamental one and is merely one of degree. 
Egg white is at once thrown down by a simple trivalent ion, such as 
lanthanum, even in a concentration of only 0'0016 molar. The 
complex trivalent ion of the luteo-cobalt salts (Mines, 1912) does not 
precipitate emulsoids, although it is nearly as effective on suspensoids 
as the simple lanthanum ion. The fact appears to be related to the 
low density of the charge on the large ion. 

On the other hand, these particular emulsoid colloids react in an 
important way to another property of salts, that property called by 
Freundlich (1909, pp. 51 and 412) " lyotropicy It is manifested by 
changes in the distribution of the solvent between the two phases, 
dependent on changes in the solvent itself. In the case of water, we 
speak of the hydration of the ions and changes in the equilibrium 
between the various states of water itself. These give rise ;o altera- 



140 REPORTS ON THE STATE OF SCIENCE. 1918. 

tions in the internal pressure, compressibility, viscosity, solubility, 
&c. The phenomena are not in relation to the valency of either ion, 
but follow a series known as that of Hofmeister (1888). The order 
of activity in anions is : — 

SON <I <C103 <N03 <C1 <gH3C00 <S04 <tart. <citrat. 

In cations . — 

NH4 <Li <Cs <Na <Rb <K. 

But the difference between individual cations is less marked than 
that between anions. This series is met with in many phenomena 
in which emulsoid colloids play a part. The action appears to be 
preceded by adsorption. 

The effect of acid and alkali in increasing the amount of water 
taken up in the swelling of emulsoid colloids has been the subject of 
experiments by Martin Fischer and G. Moore (1907), Chiari (1911) 
and others. According to Pauli (1912), the swelling is due to the 
formation of electrolyticaUy dissociated salts and the affinity of the 
protein or other colloidal ion for water. If this be the case, we see 
hovv little importance the process can have in the phenomena of 
oedema or of " acidosis," where the possible increase in hydrogen-ion 
concenti-ation is far too small to result in any salt formation with 
proteins. The experimental results of Fischer and Moore show, 
moreover, that a fairly high degree of acidity is necepsary to produce 
any significant effect. Pauli's point of view is rendered doubtful 
also by the fact that the swelling occurs in solids, ad well as dispersed 
molecules. It seems more likely that it is due to a change in the 
properties of water at the surfaces of the constituent elements of the 
colloidal masses, a change conditioned by the adsorption of inorganic 
ions at this situation. 

The opposite effects which sodium and calcium salts have in 
reversing the phases of oil and water systems and on the permeability 
of the cell membrane have been referred to in the preceding section, 
together with the necessity for the presence of both for maintenance 
of the normal cell processes. If we confine our attention only to the 
cation in its action on emulsoid systems, it is difficult to understand 
why there should be, not mei-ely a quantitative difference between 
univalent and bivalent ions, but an opposite effect. Clowes (1916, 
p. 408) holds that the opposition is really one between anions and 
cations, a more intelligible view. In the case of calcium chloride, 
for example, the cation is more powerfully adsorbed and reactive 
than the anion ; in that of sodium chloride, the anion is adsorbed to 
a greater degree than the cation. Hence the possibility of obtaining 
a balance between the two effects and the re.ison why a small con- 
centration of calcium chloride balances a mach larger one of sodium 
chloride. This view is confirmed by the fact that much less sodium 
citrate than of sodium chloride is required to counteract the effect 
of calcium chloride, because the citric anion is more powerfully 
adsorbed than the clilorine ion. But the possibility of the production 
of complex ions, containing calcium and the citric ion, must not be 
overlooked. 

A certain difficulty arises with regard to potassium. It is found 
that to maintain normal cell processes and to permit growth the 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIOxVS. 141 

presence of a small concentration of potassium salt is necessary in 
addition to that of sodium and calcium. We may perhaps be satisfied 
with the statement that potassium is required on account of particular 
chemical properties. This appears to be the view taken by Loeb and 
Cattell (1915), but, as we have no idea as to what these properties 
are,, very little is gained. Some recent work by Zwaardemaker (1918) 
is of importance with respect to the elucidation of the problem. 
This observer noticed that the elements which Ringer found to be 
able to replace potassium, namely, rubidium and caesium, are, like 
potassium, weakly radio-active and he proceeded to test other sub- 
stances more powerfully radio active, such as radium itself, emanation, 
uranium, and thorium. It was found that equally radio-active con- 
centrations of all the elements named were equal in their capacity of 
replacing potassium in a solution adequate to maintain normal cell 
life. 

Sodium salts are chosen to make up the correct osmotic pi'essure 
of these fluids because they are the least toxic salts. But Clark (1913, 
p. 77) found that a better solution was obtained if a part of the 
sodium chloride was replaced by its osmotic equivalent in cane-sugar. 

Some very interesting conclusions have been drawn by Macallum 
(1904) from the fact that the salts present in sea water form an appro- 
priately balanced mixture for the cells of the higher vertebrates, 
when the sea water is diluted to the correct osmotic concentration. 
It seems evident that the electrolyte composition of the blood of the 
present land vertebrate is that of the ocean at the close of the 
Cambrian period, when their ancestors left the water and took to ihe 
land. The Cambrian period was an extremely long one and the 
colloidal systems of the cell were developed in adjustment to this 
balanced mixture of salts. But at the same time, it is a remarkable 
fact that the particular mixture arising from the dissolving of con- 
stituents of the earth's surface should be that of a " balanced " 
solution, not only for protoplasm, but also for emulsions of oil and 
water. 

There is another interesting way in which the relationship of 
colloids to electrolytes meets us in physiological phenomena, namely, 
the mechanism of muscular contraciion. Blix (1891) and A. V. Hill 
(1913) have shown conclusively that the tension developed is pro- 
portional to the area of certain surfaces arranged longitudinally in 
• the muscle and is not a volume effect. Fitzgerald (18/8) and Bern- 
stein (1901) had already suggested surface tension at the contact 
between the fibrillae and sarcoplasm as the mode of production of the 
muscular force, and there are other facts which confirm the view 
that surface phenomena form a component pai't of the complex of 
events. Surface tension has the peculiarity of possessing a negative 
temperature coefficient, doubtless connected with the absence of any 
boundary surface at the critical temperature. The contractile stress 
produced by muscle has a negative temperature 'coefficient (Bernstein, 
i908), as also has the heat produced in the initial stage. Lactic acid 
is one of the chemical products of the muscular process, and Haber 
and Klemensiewicz (1909) put forward the hypothesis that the acid 
alters the electrical forces at the boundary between the fibrilhc and 
the sarcoplasmic liquid. This again involves a change of surface 



142 EEPOKTS ON THE STATE OF SCIENCE. — 1918. 

tension, which brings about the mechanical shortening of the fibres. 
The negative temperature coefficient excludes swelling of colloidal 
fibrils under the influence of acid as accounting for the muscle 
process as suggested by some. The imbibition of water has a positive 
coefficient. 

BiBLIOGKAPHY. 

Bayliss, W. M. (1906), ' Biochem. Journ.' 1, 175. 

' On Some Aspects of Adsorption Phenomena, with Especial Reference to the 
ActioDi of Electrolytes and to the Ash Constituents of Proteins.' 
Bernstein, J. (1901), ' Pfliiger's Archiv.,' 85, 271. 

' Die Energie des Muskels als Oberflachenenergie.' 
Bernstein, J. (1908), ' Pfliiger's Archiv,' 122, 129. 

' Ueber die Temperaturcoefficienten der Muskelenergie.' 
Blix, M. (1891), 'Skand. Arch. Physiol.', 3, 295, and 5, 150. 

' Die Lacge und die Spannnng des Muskels.' 
BuGARSKY, S. and Liebermann, L. (1898), Pfliiger's Archiv.,' 72, 51. 

'Ueber das Bindungsvermogen eiweiisartiger Korper fur Salzsaure, Natrium 
hydroxide und Kochsalz.' 
Chiaki, R. (1911), ' Biochem-Zeitschr.' 33, 167. 

' Die Glutinquellung in Sauren und Laugen.' 
Clark, A. J. (1913), 'Journ. Physiol.' 47, 66. 

' The Action of Ions and of Lipoids upon the Frog's Heart.' 
Clowes, G. H. A. (1916). 'Journ. Physic. Chem.,' 20- 407. 

' Protoplasmic Equilibrium. Action of Antagonistic Electrolytes on Emulsions and 
Living Cells !' 
Fischer, M. H., and G. Moore (1907), ' Amer. Journ. Physiol.,' 20, 330. 

' On the Swelling of Fibrin.' 
Fitzgerald, G. F. (1878), 'Scientific Trans. Roy. Dublin Soc' (1878). 

' On the Superficial Tension of Fluids and its possible Relation to Muscular 
Contraction.' ' 

Also in ' Scientific Writings of the late G. F. Fitzgerald.' Edited by J. Larmor 
(1902), p. 34. 

Freundlich, H. (1909), ' Kapillarchemie,' Liepzig, Akad. Verlag., 591 pp. 
Freundlich, H., und Schucht, H. (1913), ' Zeitschr-physik. Chem.,' 85, 641, 

' Die Bedeutung der Adsorption bei der Fallung der Suspensionskolloide.' 
Habee, F., und Z. Klemknsiewicz (1909), ' Zeitschr. physick. Chem.,' 67, 385. 

' Ueber elektrische Phasengrenzkrafte.' 
Hardy, W. B. (1905-6), 'Journ. Physiol,' 33, 151. 

' Colloidal Solutions. The Globulins.' 
Hardy, W. B. (1910), 'Gedenkboek Van Bemmelen.' Te Helder, De Boer, p. 1^0. 

' Electrolytic Colloids.' 
Hill. A. V. (1913), ' Journ. Physiol,' 46, 435. 

' The Absolute Mechanical Efficiency of the Contraction of an Isolated Muscle.' 
HOFMEISTER, F. (1888), ' Arch. Exper. Pathol.,' 24, 247. 

' Zur Lehre von der Wirkung der Salze.' 
HuFNER, G., und E. Gansser (1907). ' Arch. (Anat, u.) PhysioL (1907), p. 209. 

' Ueber das Molekulargewicht des Oxyhaemoglobins.' 
ISHIZAKA, N. (1913), 'Zeitschr. physik. Chem.,' 83, 97. 

' Ueber die Beziehung zwischen Kolloidfallung und Adsorption.' 
Lewis, W. C. McC. (1909), ' Kolloid. Zeitschr.,' 4,211. 

' Grosse und elektrische Ladung der Oelteilchen in Oel-Wasser-Emulsionen.' 
LOEB, J. (1918), 'Journ. Biolog. Chem.,' 33, 531. 

' lonisation of Proteins and Antagonisiic Salt Action.' 
LoEB. J., and McKeen Cattell (1915). ' Journ. Biolog. Chem.,' 23, 41- 

' The influence of Electrolytes upon the Diffusion of Potassium out of the Cel 
and into the Cell.' 
Macallum, a. B. (1904), 'Trans. Canadian Inst.' (Reprinted). 30pp. 

' The Palffiocheuiistry of the Ocean in Relation to Animal and Vegetable 
Protoplasm.' 
Mines, G. R. (1912), 'Kolloid. Chem. Beihefte,' 3, 191. 

' Der Einfluss gewisser lonen auf die elektrische Ladung von Oberflachen und 
ihre Beziehung zu einigen Problemen der KoUoidchemie und Biologie.' 



ON COLLOID CIIESXLSTRY AND ITS INDUSTRIAL Ai'PLICATIONS. 143 

Pauli, W. (1910), ' Pflu-rer's Arch.,' 136, 483. 

' Die koUoiden Zustandsiinderunijen von Eiweiss und ihre physiologisclie Bedeu- 
tung.' 
Peerin, J. (100-t, 1905), ' Journ. Chimie physique," 2, 601 ; 3, 50. 

' Mecanisme de I'electrisation de contact et solutions coUoidales.' 
Pfkipfer, p., und J. v. Modelski (1912), ' Zeitschr. physiol. Chem.,' 81, ■'529 ; 85, 1. 

' Verhalton der a-amino-sauren und Polypeptide gegeu Neutralsalzen.' 
ZwAARDEMAKER, H. (1918), 'Amer. Journ. Physiol.' 45, U7. 

' Aequiradio-Activity.' 

(Radioactivity of potassium in relation to its physiological action.) 

IV. Enzymes. 

In the present report, that aspect only of the action of enzymes 
■which is related to their colloidal nature will be discussed. 

The fact that enzymes are present in their solutions in the colloidal 
state is shown by their non-diffusibility through parchment paper, 
and is now generally recognized. Taking this fact into consideration, 
together with the form of the relation between the concentration of 
the substi^ate and enzyme and the velocity of the reaction, the present 
writer (1908) put forward the hypothesis that the chemical decom- 
position of the substrate is preceded and controlled in rate by 
adsorption. Not only, however, are enzymes in the colloidal state, 
but they are able to act in a medium in which they are insoluble and 
present as coarse particles which can be filtered off, leaving the 
filtrate inactive. This has been shown in the case of lipase by 
Dietz (1907), in that of emulsin by Bourquelot et Bridel (1913), by 
myself (1915) for lactase, papain, peroxidase, catalase, urease, and 
invertase, with great probability for trypsin and pepsin. Armstrong, 
Benjamin and Horton (1913) came to the conclusion that urease acts 
by its surface. A similar conclusion may be drawn from the fact 
that invertase may be adsorbed by charcoal and nevertheless remain 
active (Nelson and Griffin, 1916). We may conclude, then, that 
enzymes belong to the class of catalysts present as a separate phase 
and acting in a heterogeneous system. 

The next question that arises concerns the mechanism of their 
action. 

There are two theories of catalysis in heterogeneous systems : 
one of these assumes the formation of an intermediate unstable 
chemical compound between the catalyst and substrate, the reaction 
following the ordinary laws of mass action ; the other regards the 
chemical change as being brought about, or rather greatly accelerated 
by close approximation of the reacting substances by condensation on 
the surface of the catalyst by adsorption. An intermediate position 
is taken by those who regard the rate of the reaction as conditioned 
by the amount of reagents present on the surface at any given time, 
but hold that the actual chemical change is due to formation of a 
chemical compound with the substance of the catalyst itself, occurring 
as a second stage of the complete process. This process may be ex- 
pressed as made up, in order, of adsorption, combination with 
enzyme, decomposition of intermediate compound, with enzyme left 
finally as at first. 

As a typical instance of the first view, we may take Van Slyke and 
CuUen's (1914) account of the kinetics of urease. These observers 
state that the action consists of two consecutive roaotions : (1) com- 



144 REPORTS ON THE STATE OF SCIENCE. 1918. 

bination of enzyme with urea, and (2) breaking up of the compound, 
the urea being freed in the form of ammonia and carbon dioxide. 
They formulate an expression of two factors, each with an empirical 
constant, which, by proper choice of the two constants, satisfies the 
experimental data. This fact, however, does not prove that the first 
stage is a chemical combination. Indeed, it is stated that the first 
stao'e, combination between enzyme and urea, is so rapid that no 
appreciable time is lost. If this be so, it is difficult to see why it 
appears in the equation at all. The authors seem to hold that 
physical phenomena, such as adsorption, diffusion and so on, follow 
indefinite laws only, in contradistinction to those of chemical com- 
bination. Further remarks with reference to formulae based on mass 
action alone, will be found below. Although the work in question is 
the most clearly expressed statement of the particular point of view, 
the theory itself is probably the most widely accepted one as applying 
to enzymes. Incidentally, we may remark that the fact that a par- 
ticular reaction appears to follow the ordinary unimolecular law of 
velocity, deduced from mass action, is no guide to the nature of the 
process as a whole. Denham's (1910) reaction, in which a sheet of 
platinum is the catalyst, follows this law. 

For the first statement of the other view, we must go back to 
Faraday (1884). The experiments and conclusions to be found in 
his paper, ' On the Power of Metals and other Solids to Induce the 
Combination of Gaseous Bodies,' are apt to be forgotten, so that I 
make no excuse for referring to them in some detail. The phenomena 
in question are the combination of oxygen (and nitrous oxide) with 
hydrogen, induced by the surface of metallic platinum and other 
solids. In paragraph 619, Faraday states ' All the phenomena con- 
nected with this subject press upon my mind the conviction that 
they are dependent upon the 7iatural conditions of gaseous elasticity, 
combined with the exertion of that attractive force possessed by 
many bodies, especially those which are solid, in an eminent degree, 
and probably belonging to all ; by which they are drawn into asso- 
ciation more or less close, without at the same time undergoing 
chemical combination, though often assuming the condition of 
adhesion ; and which occasionally leads, under very favourable 
circumstances, as in the present instance, to the combination of 
bodies simultaneously subjected to this attraction.' That the phe- 
nomena are regarded as a condensation on the surface, not a solution 
in the substance of the solid, is clear from the reference to hygro- 
metric. bodies which ' condense water vapour aroiind or upon their 
surface,' and are said to be instances of the same power (par. 621). 
The absence of chemical combination with the surface is stated 
clearly in par. 631, ' The plitina is not considered as causing the 
combination of any particles with itself, but only associating them 
closely aroiind it ; and the compressed particles are as free to move 
from the platina, being replaced by other particles, as a portion of 
dense air upon the surface of the globe, or at the bottom of a deep 
mine, is free to move, by the slightest impulse into the upper and 
rarer parts of the atmosphere.' Par. 632 calls attention to a fact 
which is common to adsorption phenomena in general, and is of 
importance in certain effects of retarding agents on enzymes, as we 



ON COLLOID CHEMISTRY AND ITS INDUSTniAL APPLICATIONS. 145 

shall see presently. ' It can hardly be necessary to give any reasons 
why platina does not show this effect under ordinary circii instances. 
It is then not sufficiently cK-an (t)17), and the gases are ])reventeil 
from touching it, and suffering that degree of effect which is needful 
to commence their combination at common temperatures, and which 
they can only experience at its surface. In fact, the very power 
which causes the combination of oxygen and hydrogen is competent, 
under the usual casual exposure of platina, to condense extraneous 
matters upon its surface, which, soiling it, take away for the time 
its power of combining oxygen and hydrogen, by preventing their 
contact with it ' (598). Numerous facts are described which show 
that the only condition necessary is a perfectly clean surface, however 
produced. One way of doing this is of theoretical importance as 
showing that the action is not due to chemical combination of either 
oxygen or hydrogen with platinum. Platinum can be made active 
by making it eithfer anode or cathode of an electrolytic cell (*)17). 
Chemical action is also excluded by the fact that nitrons oxide and 
hydrogen can be made to combine (572X and also by the fact that 
the 'effect is produced by most, if not all, solid bodies' in varying 
degree (618). It may be said that gas reactions only are contemplated 
in this theory, but statements in pars. 6215, 625, and 657 indicate 
that Faraday had in mind the possibility of similar reactions in 
liquids. Indeed, the following statement is remarkably like an 
anticipation of Van Hoff's theory of solutions, ' An analogy in 
condition exists between the parts of a body in solution and those of 
a body in the vaporous or gaseous state.' 

Denham (1910) brings powerful evidence in support of this 
theory of catalysis in inorganic heterogeneous systems as being 
due to the high surface concentration caused by molecular forces 
at the surface, and the high velocity of reaction as being due to 
the increased mass action thus brought into play. Bancroft (1918) 
gives a valuable discussion of contact catalysis. 

Denham, however, although he is of the opinion that some 
enzyme effects may be accounted for in a similar way, hesitates tc 
apply the theory to all enzymes. We may, therefore, proceed^ to 
examine the efidence bearing on the question. But before doing 
this, we should remember that it is possible, as Hardy points out 
(see paper by Drury, 1914), that there may be, in addition to the 
simple mass effect, an increased chemical potential of the reacting 
molecules brought about by the actual process of condensation 
itself and the stresses which it involves. 

That the rate of reaction is controlled by adsorption is evident 
from various facts. The law expressing the way in which the 
concentration of enzyme and of substrate is related to the rate 
of change is not one that could be deduced from mass action. Up 
to a particular concentration of substrate, which varies with different 
enzymes, the law followed is that of a parabolic curve, similar to 
that of adsorption, although this, of course, does not in itself prove 
that we have to do with adsorption. Beyond this particular con- 
centration, the rate is either constant, whatever the concentration 
of the substrate, or, owing to some secondary effects of the enzyme, 
is actually diminished. This fact is easily accounted for by the 



146 KEPORTS ON THE STATE OF SCIENCE. — 1918. 

familiar fact that a surface may become saturated ; so that, above 
a certain concentration of the substrate, no more can be adsorbed 
at a given moment of time. On other hypotheses explanation is 
very difficult. Data showing the fact in the case of enzymes are 
numerous ; those of Frankland Armstrong (1904) with lactase may 
be particularly mentioned. 

When attempts are made to express in mathematical formulae 
the velocity of reaction with enzymes, starting with the usual expres- 
sions based on mass action, it is found that numerous empirical factors 
have to be introduced in oi'der to obtain adequate expressions. Since 
-we do not know the meaning of these factors, it seems to the writer 
that very little is gained by such procedures. The difficulty is to 
know exactly what is the active mass at any moment. It is clearly 
some function of the concentration of the substrate, because this 
determines the amount adsorbed, but it is also related to the 
adsorbing capacity of the enzyme surface, which is itself affected 
by numerous intiuences, prolaably changing during the progress 
of the reaction itself. 

According to the theory of Nernst concerning reactions in 
heterogeneous systems, there are three stages — diffusion of the 
reagents to the surface, adsorption on this surface, and finally 
chemical reaction with each other or with the constituents of the 
surface itself. The stage of adsorption is very rapid when the 
reagents have reached the surface ; so that, since the rate of the 
reaction as a whole is that of its slowest component, the process 
of adsorption itself does not control it. When one of the phases is 
a large mass, the time taken for the reagents to diffuse to it is an 
important component and usually longer than the actual chemical 
reaction itself. In such cases, the temperature coefficient of the 
reaction as a whole is that of diffusion, and is a low one. In the 
case of a colloidal dispersion, such as an enzyme in solution, the 
solid phase is evenly distributed throughout the system, so that the 
paths travelled by the substrate to reach the surfaces of the enzyme 
particles are very short, and the rate of the reaction is that of the 
chemical component, with the temperature coefficient of a chemical 
reaction. It seems likely that the coarsely heterogeneous systems 
of urease or emulsin in alcohol would be found to have the tem- 
perature coefficient of diffusion, but they have not been investigated 
from this point of view. The failure to realize these various facts 
has led to confusion of statements regarding the impossibility of an 
adsorption process having the high temperature coefficient of a 
chemical reaction. The temperature coefficient of an enzyme 
reaction is naturally that of whatever chemical change occurs, and it 
gives us no information as to the othur components of the total 
process. 

We know from numerous investigations that when a substance is 
strongly adsorbed it is capable of displacing another substance to a 
greater or less degree from its position on the surface. Many of the j 
substances found to retard the rate of enzyme action are of this kind. 
The alcohols, urethane, saponin and so on lower surface energy 
markedly. It was natural, therefore, that Meyerhof (1914) should , 
suggest this as an explanation of their action, which was found in aj 



ON COLT.OID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 147 

series of related compounds to follow their capacities of lowering 
surface tension. It is complicated, however, by some other propei'ties 
of these agents to be referred to below. As was pointed out in the 
preceding report in connection with muscular contraction, surface 
energy is peculiar in having a negative temperature coefficient. If 
the inhibiting effect i^roduced by saponin, etc., has the cause 
suggested it should be found to be greater at a low temperature, just 
as the degree of adsorption in general is well known to be greater at 
a low temperature. The present writer (l',)18j in experiments with 
saponin and with amyl alcohol showed that this actually was the case. 

A practical point of interest is the effect of alcohol on digestion. 
As far as the rate of action of the digestive enzymes on food is 
concerned all experimental evidence shows it to be a retarding one, 
and the reason is doubtless that given above. 

Remembering that the action of enzymes is a surface one it is 
clear that any agents affecting the state of disjjeision must affect the 
intensity of action. Any agent which increases the degree of 
dispersion increases the total surface and hence the activity of the 
enzyme. This factor comes in to complicate the case discussed above, 
since agents lowering surface tension tend to increase dispersion and 
thus to counteract the inhibiting effect. A particularly marked case 
is the accelerating effect of bile salts on the action of lipase. It was 
thought to be due to better emulsihcation of the oil used as substrate 
until it was found to be present also when soluble esters, such as 
ethyl acetate, were used. It seems, therefore, that it must be due in 
part to greater dispersion of the enzyme itself. 

The possibilities of complexity of action are obviously greater in 
the action of electrolytes, because we have in addition the intervention 
of electrical forces and the effects of electrical adsorption. Some of 
these may decrease, others increase, the state of dispersion, according 
to the sign of charge on the enzyme particles. In the investigation 
of the effects of substances added to solutions of enzymes we have 
then a multiplicity of factors to take into account, so that analysis of 
the phenomena is very difficult and much further work is required. 
The experiments of Onodera (1915) are of interest in this connection. 

We may regard it as established that adsorption of substrate by 
enzyme particles is the controlling factor in the velocity of the 
chemical reaction that follows. But is this adsorption followed by 
chemical combination with the enzyme, forming an intermediate 
compound of an unstable nature which thtm breaks up into products 
different from those substances from which it was formed ? In the 
majority of cases, the chemical change involved is one by which the 
elements of water are either added or removed, but this is not always 
the case. There is every reason to I'egard the effect of an enzyme as 
an acceleration of the rate at which a given system attains its equili- 
brium position, the final products being the same as those which 
would have been formed, very slowly, in the absence of the enzyme. 
There is no inherent difficulty in the view that the concentration on 
the surface results in the rapid attainment of equilibrium bj' increased 
mass action, in the same way as Faraday explained the platinum 
effect and as Denham regards the inorganic heterogeneous catalysts in 
general to produce their results. This last observer points out that 



148 REPORTS ON THE STATE OF SCIENCE. 1918. 

there is only one case in which evidence of a kind of intermediate 
compound of a chemical nature has been brought forward. So far as 
I am aware, no compound between enzyme and substrate has been 
shown to exist. Adsorption compounds or colloidal complexes have 
been obtained when the substrate is in the colloidal state, as between 
starch and amylase, and between trypsin and casein. But such com- 
pounds are formed whether the substrate is one capable of attack by 
the enzyme or not. Thus, amylase forms a similar compound with 
casein and with starch, and it appears to be a mere physical juxta- 
position of the colloidal particles, held together by mechanical or 
electrical forces. 

A certain amount of evidence that adsorption alone can increase 
the rate of change is afforded by some experiments which the present 
writer made with powdered charcoal and urea solution. Urea in 
solution, as Walker and Hambly (1895) showed, is slowly changed 
into ammonium cyanate, up to a certain equilibrium position. This 
is followed by a further change into ammonium carbonate. The 
rate of this change is accelerated to a marked degree by the presence 
of powdered charcoal. 

The absence of an intermediate compound is more definitely in- 
dicated in the investigation of Horace Brown (1914) on some Cape 
wines, where an oxidation proceeds under the influence of a catalyst 
consisting of iron in the ferrous state associated with lannin and 
protein. This acts as a ' carrier of oxygen,' as in Fenton's reaction. 
The observations of Moore and Webster (1918) on the photosynthesis 
of formaldehyde in presence of inorganic colloids are also to the 
point. They show that the effects are not due to changes of the 
catalyst from a higher to a lower oxide, but to a surface condensation 
of carbon dioxide on the particles. The effect is given indeed by 
silicic acid, in addition to ferine and uranic hydroxides and beryllium 
chloride, also, to a less extent, by copper, nickel, palladium, man- 
ganese and erbium salts. The bearing of this fact on the problem of 
chlorophyll assimilation in plants is obvious. It suggests that the 
function of the pigment in the chloroplasts is to absorb light energy 
which is then utilized by the aid of an iron catalyst to reduce 
carbonic acid to formaldehyde. 

It has been pointed out to me by Prof. Hopkins that if the pro- 
cess is to be regarded as the rapid attainment of the natural equilibrium 
in consequence of condensation on the surface of the enzyme, it 
follows that all the constituents of the system must be adsorbed in 
the same relative proportion as in the body of the liquid, otherwise 
there must be a change in the equilibrium position. 1 have made 
some experiments to test this deduction, but the difficulties are great 
and the work is for the present interrupted. I found, however, that 
a mixture of ethyl alcohol, acetic acid, ethyl acetate and water, after 
equilibrium had .taken place, was unaltered by the addition 6f 
powdered charcoal, although charcoal is known to adsorb some of 
the constituents, at all events. The result indicates that the various 
constituents must" have been adsorbed in the same proportion as that 
in which they were present in the mixture. But further experi- 
ments are desirable and it does not follow that enzymes behave like 
charcoal. Curiously enough, it appears to be well established that, 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 149 

in the case of esters at least, the equilibrium position is not the same 
with acid as catalyst as with lipase (Dietz, l'J07). In the former 
case, the equilibrium' is with 85-5 per cent, ester (amyl butyrate) ; in 
the latter, with 75 per cent, ester. The equilibrium is a genuine one 
in both cases, since it can be reached from either direction. If water 
were more highly adsorbed from this mixture than the other con- 
stituents, the result, which shows more hydrolysis than in the case of 
acid, might be explained. The fact has given rise to many conjec- 
tures, on account of the fact that it seems to give an opportunity to 
evade the second law of thermodynamics. The considerations given 
above add yet another, namely, that the fact may be due to unequal 
adsorption. Whether the equilibrium on the surface of enzymes is 
of necessity the same as that in the body of the solution is not yet 
quite clear and this point requires investigation. A.t any rate, there 
seem to be no inherent difficulties in the hypothesis suggested. The 
relative degree of adsorption of the various constituents of a mixture 
has received some attention, especially by Arrhenius and others 
working with him (see Williams, 1913). It is clear that all are 
adsorbed, including the solvent itself. 

Some interesting possibilities are pointed out by Bancroft (1918). 
If different products can be obtained from a particular substance, it 
may happen that one catalyst adsorbs certain of them more power- 
fully than another one does, so that the resulting equilibrium may 
not be the same in the two cases. Similarly, different catalysts, such 
as platinum, charcoal, clay, etc., may cause different forms of com- 
bination in a mixture of gases, according to th«ir relative adsorp- 
tion. If one of the products of a reaction is very strongly adsorbed, 
it may possess the surface to such an extent as to stop farther action 
and produce a false appearance of equilibrium, the position of which 
will depend on the concentration of the catalyst, contrary to the true 
equilibrium. 

The question of synthesis by enzymes does not properly belong 
to the scope of this report, but it is clear that, since the characteristic 
of catalysis is the rapid attainment of a natural equilibrium, depend- 
ing on the relative concentration of the components of the system, 
the same enzyme will exhibit either hydrolytic or synthetic activity 
according to the composition of the mixture." Synthetic action 
requires a low concentration of water (see especially Armstrong and 
Gosney, 1911), so that, as pointed out previously, a method is wanted 
by which the cell can vary the effective concentration of water. No 
special synthesizing enzymes are called for. The evidence that has 
been brought for the existence of such agents in not convincing (see 
Bayliss, 1913). 

The chief difficulty in regarding the mode of action of enzymes 
as consisting merely in a surface condensation of the constituents 
of the reacting system is the apparently specific nature of these 
catalysts, although the degree of specificity is probably exaggerated. 
We must remember that the nature of the surface determines 
adsorption, since all the physicid properties of a substance depend 
on its chemical nature. The i)OSsibilities of different adsorption 
properties are enormous and the study of the subject is yet in its 
infancy. One of the most interesting cases of this specific action is 



150 REPORTS ON THE STATE OF SCIENCE. 1918. 

that of those enzymes which act on optically active compounds and 
the synthesis of such compounds by optically active catalysts (see 
Bredig and Fajans, 1898, and Bredig and Fiske, 1912). 

Bibliography. 

Armstrong, E. Frankland (1904), ' Proc. Roy. Soc.', 73, 500. 

' The Rate of Change conditioned by Sucroclastic Enzymes and its Bearing on 
the law of Mass Action.' 
Armstrong, H. E., M. S. Benjamin and E. Hoeton (1913), ' Proc. Roy. Soc.', 86 B,328. 

'Urease, A selective Enzyme. II. Observations on Accelerative and Inhibitive 
Agents.' 
Aemstkonq, H. E., and H. W. Gosney (1914), ' Proc. Roy. Soc.', 88 B, 176. 

' Studies in Enzyme Action, xxii, Lipase, iv. The Correlation of Synthetic and 
Hydrolytic Activity.' 

Bancroft, Wilder D. (1918), ' Jonm. Physic. Chem.' 21, 573 and 22, 22. 
' Contact Catalysis,' I. General Theory, 21, 573. 

II. Fractional Combustion, 21, 644. 

III. Poisons, 21- 734. 

IV. False Equilibria, 22, 22. 
Bayliss, W. M. (1906), ' Biochem. Journ.', 1, 175. 

' On some Aspects of Adsorption Phenomena,' etc. 
Bayliss, W. M. (1913), ' Journ. Physiol.', 46, 236. 

' Researches on the Nature of Enzyme Action, iii., ' The Synthetic Action of 
Enzymes.' 
Bayliss, W. M., (1915), ' Journ. Physiol.', 50, 85. 

' The Action of Insoluble Enzymes.' 
Bayliss, W. M. (1918), ' Arch. Neerland,' II. 4=, 621. 

' Enzymes and Surface Action.' 
BouEQUkLOT, E., et M. Bridel (1913), ' Ann. Chim. et Physique,' 28, 1*5- 

' Synthese des glucosides d'alcools a I'aide de I'emulsine et reversibilite des 
actions fermentaires.' 
Bredig, G., und K. Fajans (1898), ' Ber. Deutsch. Chem. Ges.', 41, 752. 

' Zur Stereochemie der Katalyse.' 
Bredig, G., und P. S. Fiske (1912), ' Biochem. Zeitsch.' 46, 7. 

' Durch Katalysatoren bewirkte asymmetrische Synthese.' 
Brown, Horace (1914), 'Journ. Inst. Brewing', 20, 3^5- 

' An Account of some Investigations on the White Wines of South Africa : an 
Oenological Study.' 
Denham, H. G. (1910), Zeitschr. physik. Chem.', 72, 641. 

' Zur Kenntnis der Katalyse in heterogenenlSystemen.' 
Dietz, VV. (1907), ' Zeitschr. physiol. Chem.', 52, 279. 

' Ueber eine umkehrbare Fermentreaktion im heterogenen System : Esterbildung 
und Esterverseifung.' 
Drury, Alan N. (1914), ' Proc. Roy. Soc.', 88 B, 166. 

' Tbe Validity of the Microchemical Test for the Oxygen Place in Tissues.' 
Faraday, Michael (1834), 'Phil. Trans. Roy. Soc' (1834). 

' On the Power of Metals and other Solids to induce the Combination of Gaseous 
Bodies.' 
Meyerhof, 0. (1914), ' Pfliiger's Archiv.,' 157,251. 

' Ueber Hemmung von Fermentreaktionen durch indifferente Narkotika.' 
Moore, B., and T. A. Welsteb (1918), 'Proc. Roy. Soc.,' 90 B, 168. 

' Action of Light Rays on Organic Compounds, and the Photo-Synthesis of 
Organic from Inorganic Compounds in Presence of Inorganic Colloids.' 
Nelson, J. M., and E. G. Griffin (1916), 'Journ. Amer. Chem. Soc.,' 38, 1109. 

' Adsorption of Invertase.' 
Onodera, N. (1915), ' Biochem. Journ ,' 9, 544. 

' On the Effects of Various Substances (Electrolytes, Non-Electrolytes, Alkaloids, 
etc.) upon the Urease of Soy-Bean.' 
Slyke, D. D. VAN, and Glenn E. Ccllen (1914), 'Journ. Biol. Chem.', 19, 141. 

' The Mode of Action of Urease and of Enzymes in General.' 
Walker, J., and F. J. Hambly (1895), ' Trans. Chem. Soc.,' 67, 746. 

* The Transformation of Ammonium Cyanate into Urea.' 
Williams, A. M. (1913), ' Meddel. K. Vetenskapsak,ad. Nobelinstitut,' 2, No. 27. 
' On Adsorption from Solutions.' 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 151 



V. The Transport of Gases in Animals. 

Oxygen is continually being used up and carbon dioxide produced 
by the oxidation of food materials in the tissues of animals. When 
the current of blood flowing in a given time is compared with the 
consumption of oxygen and the carbon dioxide produced in the same 
time it is clear that, in neither case, is the amount that could be 
carried in solution in the liquid of the blood nearly sufficient to 
account for that actually transported. 

Both these gases, therefore, must be carried in some kind of 
combination with substances present in the blood. It will clear the 
way if we exclude certain possibilities at once. Oxygen is taken up 
by the blood in the air sacs of the lungs, where its partial pressure is 
about 100 mm. of mercury. The venous blood has an oxygen tension 
of about 37 mm. of mercury. Accordingly, the substance serving 
for the transport of oxygen must be one which takes up oxygen 
when exposed to a tension of this gas of 100 mm. and gives it off 
again, more or less completely, at 37 mm. or thereabouts. The 
tension of carbon dioxide in the lungs is 40 mm. of mercury ; in the 
blood arriving from the tissues about 61 mm. or thereabouts. The 
substance transporting this gas must be one that takes up carbon 
dioxide at 61 mm. and gives it off at 40 mm. There is only one 
substance present in the blood that has the requisite properties as 
regards oxygen, that is the i-ed colouring matter of the red blood 
corpuscles, haemoglobin. This has been known for a long time. But 
some confusion has arisen with regard to carbon dioxide, because 
solium bicarbonate is present in the blood plasma, and it was natural 
to look upon this as the carrier. Bohr (1891), however, had already 
shown that sodium bicarbonate gives off no carbon dioxide to the 
gas at a pressure of 40 mm. of mei"cary, and Buckmaster (1917) has 
confirmed this statement. The latter observer has also shown that 
there is no substance present in the blood acting as an acid to drive 
off the carbon dioxide. There seems to be no possibility of a dis- 
sociable compound of carbon dioxide with the proteins of the blood 
plasma. We have seen that proteins do not combine with weak acids, 
although a process akin to adsorption may occur, although it is not 
definitely shown to be present. The part played by the proteins is 
as yet somewhat uncertain, but the work of Buckmaster has proved 
that by far the greater part of the carbon dioxide, if not all, is carried 
by the haemoglobin in a manner similar to that in which it carries 
oxygen. 

The function of the sodium bicarbonate, as Lawrence Henderson 
(1908) has so well shown, is to preserve the hydrogen-ion concen- 
tration of the blood within narrow limits. 

The work of Barcroft and his coadjutors has brought out in 
detail the relations between oxygen and haemoglobin, under various 
conditions, and shown how the facts can be expressed in a mathe- 
matical form. A complete account will be found in Barcroft's book 
(1914). The object of the present report is to point out the difficulties 
met with when an attempt is made to reconcile the interpretation 
sometimes given to these expressions with the fact that haemoglobin 
exists in the blood as a heterogeneous phase. In the corpuscles the 



152 REPORTS ON THE STATE OF SCIENCE. — 1918. 

concentration of haemoglobin is about 30 per cent. No solution of 
haemoglobin of this strength can be made. Even in 5 per c^nt. it 
forms a colloidal suspension, and it does not diffuse through parchment 
paper, however dilute the solution may be. 

Barcroft explains the phenomena on the basis of chemical com- 
bination between oxygen and hfemoglobin, a series of compounds, 
HbOo, Hb204, HbgOs, &c., being formed in different relative pro- 
portions according to the electrolytes present in the solution. These 
electrolytes are regarded as causing aggregation of haemoglobin 
molecules ; the aggregate Hb^, when it combines with two molecules 
of oxygen, leads, by mass action, to a different order of equation 
from that of Hb and O2, which is unimolecular. But it is not yet 
certain that we are justified in applying the law of mass action in a 
simple form to heterogeneous systems and, if we apply the phase 
rule, we are at once met with difficulties, as will be seen below. On 
the other hand, it is not universally accepted that the phase rule 
can be applied to colloidal solutions, although the haemoglobin in 
the corpuscles may reasonably be regarded as a more definitely 
distinct phase. 

Barcroft's experimental results are of so much value that it seems 
to the writer that there is some risk of the problem being prematurely 
considered to be solved and the very remarkable character of the 
phenomena being overlooked. 

Assuming that the phase rule applies, what does it tell us .^ If 
Hb02 is a chemical compound, there are three phases present in a 
solution of it when in contact with an oxygen atmosphere, Hb, Hb02 
and oxygen. There are two components ; because Hb and HbOg vary 
inversely ; the oxygen is present in unlimited amount. There is 
therefore only one degree of freedom : 

F = C + 2-P = 2-h2-3 = 1. 

In other words, at a given temperature, say that of the blood, the 
ivlwle of the haemoglobin is either reduced or oxidized, according to 
the tension of the oxygen. But this is not the case. It is well 
known that haemoglobin varies in its content in oxygen, at the same 
temperature, according to the tension of oxygen. It is free from 
oxygen at zero tension and saturated at about 100 mm. of mercury at 
the temperature of 38° C, while it foUoM^s a particular law, expressed 
by the dissociation curve, between these values. 

Apart from this deduction from the phase rule, there are certain 
chemical systems that have been hastily assumed to be similar to that 
of oxygen and haemoglobin. We shall see that they are different and 
really obey the phase rule. 

By a misunderstanding of Le Chatelier's data (1883), the calcium 
oxide and carbon dioxide system has been supposed to throw light 
on the haemoglobin question. But, at a given temjjefcUure, the 
calcium is present either entirely in the form of calcium oxide or 
calcium carbonate, according to the tension of carbon dioxide. At 
tensions below a certain value, different for each temperature, we 
have complete decomposition ; at all tensions above this value, the 
whole exists as calcium carbonate, and there are no intermediate 
stages. At first sight, again, a solution of sodium bicarbonate in 
water seems more like the one we seek. At tensions of carbon 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 153 

dioxide between and about 3 mm. of mercury, there is a series of 
intermediate stages in which there are progressively increasing 
concentrations of the bicarbonate and decreasing concentrations of 
carbonate. But the explanation of this fact lies in the electrolytic 
decomposition of the salt. The presence of more HCO3 ions results 
in a rounding off of the coiner of the curve owing to reduced 
ionization of the salt. Again, there are some dyes which may exist 
in a reduced form, capable of takint; up oxygen when exposed to the 
air. Experiments made by W. A. Osborne (not yet published) were 
unable to discover any one of these which was not either completely 
reduced or completely oxidized, as the phase rule would jjredict. All 
search has hitherto failed to find i^ny chemical system similar to that 
of oxygen and hjemoglobin. 

It will probably occur to the reader that the adsorption of gases 
by indifferent solids, such as charcoal, is, at a given tempei-ature, in 
proportion to the tension of the gas. In fact, it was suggested liy 
Wolfgang Ostwald (1908) that the taking up of gases by haiuioglobin 
is a case of adsoi-ption. But we are met by nearly as many ditliculties 
in this view as in that of chemical combination. The taking up of 
gases by chai-coal follows the usual parabolic law, whereas that of 
oxygen by haemoglobin in solution in distilled water follows the 
rectangular hyperbola of a unimolecular reaction. On the other hand, 
the curve given by the latter system in the presence of electrolytes, 
acids or salts, requires a value greater than unity to be given to the 
exponent of the equation for the reaction velocity, in some cases above 
3, an exceptional value for the order of an equation for velocity of 
reaction. The curve approximates more to that for adsorption. 

The fact that there is a saturation point, beyond which increase 
of oxygen tension gives no measurable increase in the amount taken 
up by haemoglobin, is not in itself, of course, inconsistent with 
adsorption. But, again, it is a remarkable fact that the accurate 
determinations of Peters (1912) have shown that the amount of 
oxygen taken up in saturation is exactly that required to combine 
wiih the iron in the haemoglobin molecule to form FeOo ; in other 
words, one molecule of haemoglobin combines with one molecule of 
oxygen. It is natural to associate the iron with the taking up of 
oxygen, but there is no other compound of iron having the proper- 
ties of haemoglobin. Even the htematin, which is combined with 
a protein to form haemoglobin, behaves in a way isimilar to the 
dyes mentioned above. A further difficulty is the fact that haemo- 
globin takes up carbon dioxide, carbon monoxide and nitric oxide 
in a similar dissociable way to that in which oxygen is taken up, 
although in different amounts. Just as in adsorption, one of these 
gases drives out more or less completely another one. The absorption 
spectra of the CO and NO compounds is very like that of oxy- 
hsemoglobin, although there is a difference between all of them and 
reduced hfemoglobin. In any case it must be a remarkable chemical 
substance to combine with such dissimilar substances. According to 
Buckmaster and Gardner (191U-1911), chloroform is also taken up 
by haemoglobin, driving off part of the oxygen. 

In this connection, the relative adsorbing capacity of charcoal for 
various gases and vapours, the displacement of a weakly adsorbed 



154 REPORTS ON THi: STATE OF SClElfCE. 1918. 

gas by a more strongly adsorbed one and the " spoiling " of the 
surface by adsorbed impurities are problems of much interest and 
importance, not only in relation to the haemoglobin question, but 
especially in relation to the properties of the material used for the 
box respirator for protection against poison gases. It will be 
remembered that Faraday showed how readily the activity of platinum 
was stopped by the deposition of impurities from the air of the 
laboratory and that they could be driven off by heat. Investigations 
on these lines, from certain aspects, have been carried out by the 
Anti-gas Department, but are not yet made public. Bancroft (1918) 
states that carbon monoxide decreases the action of platinum in 
causing combination between oxygen and hydrogen gases and that it 
is tenaciously retained by the surface. 

When haemoglobin " combines " with oxygen, heat is evolved, 
but the results obtained by different investigators vary so much that 
it is scarcely worth while quoting them. It is well known that 
adsorption of gases by charcoal is attended by evolution of heat, so 
that the fact does not exclude the hypothesis of adsorption by 
haemoglobin. The condensation of a gas on the surface is equivalent 
to a reduction of volume by compression. 

The behaviour of the oxy-haemoglobin system to a rise of temper- 
ature is similar to that of an adsorption process. That is, the rate at 
which oxygen is taken up is increased, but the amount held in 
equilibrium is less than at a lower temperature. 

There are thus difficulties involved in both views, that of chemical 
combination and that of adsorption. It may be that the explanation 
may be found in a double process, such that the amount of oxygen 
taken up at a given tension is determined by the amount adsorbed, 
and that the adsorption is followed by chemical combination. But it is 
by no means easy to undei'stand the mechanism of such a process. 
At any rate, it is obvious that haemoglobin is a very extraordinary 
chemical compound and that its relation to gases is far from being 
explained up to the present. 

BiBLIOGEAPHT. 

Bakceoft, Wilder D. (1918), ' Journ. Physic. Chem.,' 21) 734. 

' Contact Catalysis, III., Poisons.' 
Bancroft, J. (1914). 

' The Respiratory Function of the Blood,' Cambridge : 320 pp. 
Bohr, C. (1909), 'Nagel's Handbuch der Physiol.,' 1, 54. 

' Blutgase und respiratorische Gaswechsel.' 
EUCKMASTER, G. A. (1917), ' Journ. Physiol.,' 51, 105 and 164. 

' The Relation of Carbon Dioxide in the Blood.' 

' On the Capacity of Blood and Hajmoglobin to Unite with. Carbon Dioxide.' 
BucKMAsTER, G. A. and J. A. Gardner (1910-1911), ' Journ. Physiol.,' 41, 246. 

' The Composition of the Gases of the Blood in Chloroform Aneesthesia.' 
Henderson, L. A. (1908), ' Amer. Journ. Physiol.,' 21, 427. 

' The Theory of Neutrality Regulation in the Animal Organism.' 
Le Chatelier, H. (1883), 'Comptes rendus,' 102, 1243. 

' Sur la dissociation du carbonate de chaux.' 
ObTWALD, Wo. (1908), ' Kolloid Zeitschr.,' 2, 264 and 294. 

' Ueber die Natur der Bindung der Gase im Blut. und in seinen Bestandteilen.' 
Peters, R. A. (1912), ' Journ. Physiol.,' 44, 131. 

' GhemicaL Nature of Specific Oxygen Capacity in Haemoglobin.' 



ON COLLOID CHEMISTEYAND ITS INDUSTRIAL APPLICATIONS. 155 

THE ADMINISTRATION OF COLLOIDS IN DISEASE. 
By Alfred B. Searlb, Consulting Chemist, Sheffield. 

The general trend of pathological research has shown that the 
human body possesses in a varying d<^gree the power of protecting 
itself against diseases of a parasitic nature, and that the protective 
medium is chiefly found in the blood. 

Parasites such as bacteria do not usually kill by their mere presence 
in the body, but because they produce poisons. The body in normal 
health reacts to these poisons producing an anti-toxin which either 
neutralises the poison or kills the parasites producing it. If, however, 
the body is unable to produce such anti-toxins in sufficient quantities 
it is necessary to supply them artificially. 

Some diseases appear to be due to an alteration of the blood 
owing to the presence in it of an excess of some substance such as 
uric acid or to a deficiency of certain inorganic elements which 
appear to be necessary to effect complete metabolism. 

Modern methods of treatment therefore tend to follow four lines 
of development: 

(a) The use of purer forms of well-known remedies, such 
as quinine hydro bromide instead of a decoction of cinchona 
bark, or morphia instead of tincture of opium. 

(6) The administration of the elements or salts which are 
temporarily deficient. 

(c) The use of substances having a selective action on the 
parasites which have invaded the body (see later). 

{d) The increased production in the serum of the patient 
of the protective or curative substances which would be pro- 
duced in insufficient quantities by the body under normal 
conditions. For instance, a healthy nurse will not usually be 
attacked by the disease from which the patient sufl!ers, as the 
body will produce sufficient protective substances. In a less 
healthy person insufficient protective material is produced 
unless the corresponding stimulus is given to ensure its 
formation. 

The medicines in the first group are improved by investigating 
their chemical composition, isolating the pure alkaloid or other 
essential ingredient from the mixture ordinarily used or by prepar- 
ing the drug synthetically. There are obvious limitations to this 
procedure, and there are strong reasons for supposing that only 
a portion of even the purest drugs are required by the organism. In 
other words, the first group tends increasingly to be absorbed by one 
of the others. 

Remedies of the (&) group are relatively simple when once the 
most suitable form of administration has been learned. The chief 
difficulty of the investigator is to obtain them in a form in which 
they will react in the desired manner so as to form the correct 
chemical compound required by the tissues. E. Dubard, for instance, 
has obtained evidence that a deficiency of magnesia in the system 
facilitates the development of cancer, but he has been unable to 
retain the magnesia in the system unless it is administered iu such 



156 REPORTS ON THE STATE OF SCIENCE. 1918. 

large doses (12 grammes daily) that the excess of it produces un- 
desirable eifects. Such a difficulty clearly shows that the medicine 
has heen administered in an unsuitable form. 

The chief advances in chemistry during the past thirty years have 
been due to the development of the theory that chemical reactions 
occur between the ions or ultimate portions into which compounds 
are decomposable. Hence, an element in which the body is deficient 
must eventually be reduced either to its ionic state or to a form 
of combination which is equivalent lo it. 

In many cases, substances in a colloidal state react with an 
activity which is otherwise unobtainable. This may, in part, be due 
to the fact that when complete dissociation into ions is required the 
solutions must usually be exceedingly dilute, whereas colloidal solu- 
tions may be much stronger. Hence, the use of colloids has proved 
invaluable as a me^ns of making good the deficiency in certain 
elements from which some tissues suffer. 

Diseases which require selective remedies (group c) are chiefly 
those due to parasites, including the bacilli, micrococci, and other 
"germs" which produce certain poisons or toxins. 

A substance which exerts either a toxic or a healing action on the 
body usually shows a greater affinity for one set of tissues than for 
others. Some substances have a greater action on bact;;ria and other 
parasites than on the host, and vice versa. In other words, ':heir 
action is selective, and an ideal medicine would be one which is so 
powerfully selective as to be absolutely fatal to the parasites it is 
desired to destroy and yet wholly hai-mless to the patient. 

Ehrlich showed that a toxin is capable of producing disease only 
in those persons whose body-cells contain substances capable of 
entering into chemical combination with the particular toxin. 

The anti -toxins and bacteriolysins appear to equally definite in 
composition. Ehrlich found that an aniline dye, to which he save 
the name of trypan red, is highly toxic with respect to trypanosomic 
parasites in blood but relatively harmless to the host. 

According to Metchnikoff's popular theory of phagocytosis, the 
wandering corpuscles or leucocytes in the blood attack the 
bacteria or other parasites, but this theory has receded in conse- 
quence of the discovery by G. F. Nuttall, who, when working in 
Fltigge's laboratory in 1886, found that anthrax and other bacteria 
died rapidly in fresh blood serum without the interposition of the 
leucocytes, thus showing that the serum itself contained the 
(chemical) substances which brought about their destruction. This 
is to some extent incompatible with Erlich's endeavours to seek a 
substance which is parasito-tropic without being organo-t>-opic, 
because a drug injected into the blood stream — either directly or 
intramuscularly — does not usually exhibit any action until it has 
been taken up by the serum. Hence the organo-tropic (as distinct 
from the organo-toxic) properties of a drug are of great importance. 
So far, no substances have been found which are highly parasito- 
tropic and wholly devoid of organo-tropic properties, though many 
colloidal sols are so feebly organo-tropic as to be devoid of danger in 
any ordinary doses. In the case of elementary colloids such as 
mercury or iodine, any toxic symptoms and ill effects may be re- 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS . 157 

moved by the administration of a colloid of the opposite elecfrical 
charge (a metal to relieve an excess of non-metal and vve versa). 
Whilst, as a rule, no coagulation occurs when colloidal solutions of 
the same electric sign are mixed, if a solution of the o])portite sign 
is added coagulation occurs unless one of the colloids is in very 
large excess. Before the science of chemotherapy had advanced to 
its present stage, and even now as regards certain diseases, successful 
remedies were found by what is known as the f^erurn treatment in 
which the requisite anti-toxins are prepared by cultivating suitable 
bacteria, etc., and using the products which they have formed. 
Investigations have also been made with a view to syntheHising the 
anti-toxins (or those portions of them which are required for the 
purpose") in order to eliminate certain obiectionable fe<tures of the 
serum treatment. Endeavours have also been made to simplify the 
materials used, by supplying the body with just those elements or 
groups from which it could most rapidly prepare the material which 
would stop the progress of the disease and facilitate a cure. 

Still further investigations have shown that all the normal fluids 
and secretions of the organism are essentially colloidal in character, 
the toxins or bacterial poisons appear also to be in the colloidal state 
and to a large extent the reactions which create imtuunity to 
certain diseases are typical of those met with in ordinary chemical 
absorptions and precipitations. This at once suggests tlie importance 
of colloidal substances, both in the maintenance of health and in the 
cure of disease. 

Graham,^ to whom we owe the conception of the oolloidal state, 
clearly saw the importance of colloids for living matter, when he 
wrote, " The colloidal is, in fact, the dynamic state of matter ; 
crystalloidal being the static condition. The colloid possesses 
enerqia. It may be looked upon as the probable primary source 
of the force appearing in the phenomena of vitality. To the 
gradual manner in which colloidal changes take place may the 
characteristic protraction of chemical organic changes be referred." 
These words are prophetic of what is now recognised with regard to 
the relation of colloidal and living matter, whether healthy or 
diseased, and, so far as is known at present, the physico-chemical 
conditions necessary for life can be accurately summarised in the 
statement that all life-processes take place in a colloid si/nfem,^ only 
those structures being considered as living which are at all times in 
a colloidal state. 

According to J. Beatty,^ all enzyme action, whether of hydrolysis, 
synthesis, oxidation, or reduction, can ultimately be traced to the 
addition or removal of hydrogen or hydroxy 1 ratlicles in hydrolysis 
or synthesis, and to the replacement of H by OH or OH by H in 
oxidation and reduction respectively. In the presence of a catalyst 
the speed of reaction may be increased, or its sphere of action 
limited, the latter being controlled by the colloidal nature of 
enzymes, whereby reactions are brought about as the result of 
surface adsorption. 

'Phil. Trans. 1861, 151, 184. 

2 Wolfgang Ostwald. " Colloid Chemistry," New York, 191*. 

' " The Method of Enzyme Action," London, 1917. 



158 REPORTS ON THE STATE OF SCIENCE. 1918. 

Many animal organs behave exactly like gels when immersed in 
water and swell enormously. This swelling is affected by the 
presence of small proportions of acids, alkalies or salts in the water. 
Thus, in the case of gelatin, fibrin and egg-albumin, acid solutions of 
moderate concentration greatly increase the amount of swelling and 
the amount of water absorbed by the organic substance. This is due 
to the presence of free hydrogen ions. On the other hand, the 
addition of a suitable alkali or salt will reduce the swelling and 
restore the substance to its previous condition, by neutralising the 
excess of free hydrogen ions. If an excess of hydroxl ions be 
added in the attempt to reduce the swelling, the gel may be peptised 
and " dispersed." A typical glaucomatous state may be induced in 
sheep's eyes in vitro by immersing them in very dilute hydrochloric 
acid. The normal condition may be restored by the addition of 
ferric chloride or other appropriate salts. Precisely the same 
phenomena are observable with living tissues, both in health and 
disease, and any desired colloidal condition may be obtained in the 
latter by appropriate colloidal treatment. Thus, the administration 
of salt has been successfully employed in the treatment of nephritis 
and oedema.* The extensive use of salines solutions in various 
stages of collapse has long been practised in all civilised countries, 
and its success is due to the action of these substances on the 
colloidal serum. Such salts prevent the swelling and coagulating 
effects of the acids formed in the diseased tissues, just as they 
decrease the effect of other acids, or effect the precipitation of 
certain colloids in vitro. 

Inflammation is also a colloidal phenomenon, and is brought 
about by precisely similar conditions in the living subject, and in 
artificially prepared plates of non-living materials.^ It is easy, for 
example, to produce " artificial flea bites " by pricking a piece of 
gelatin with a needle dipped in formic acid and then placing the 
gelatin in water.'' The remedy — injecting into the swollen portion 
sufficient alkali to neutralise the acid — is as efficient as when this 
method is applied to a real bite. The complete comparison of these 
" bites " with the phenomena observed when a flea bites the human 
subject is, however, a very difficult matter. 

The unknown substance which produces goitre^ is most probably 
colloidal in nature. Hence, from one point of view, therapeutics is 
lai'gely concerned with a study of the formation of colloids which 
are abnormal in the sense that they do not occur in the natural 
processes of a healthy body, but which — when regarded as colloids — 
are no more unusual than the coagulation of a highly dispersed sol 
or the peptization of a coarser gel. The chief difficulty in the way 
of experiment or treatment is that in one case conditions are severely 
restricted owing to the fact that the colloids form part of a living 
organism. 

* M. H. Fischer, (Edema and Nephritis, New York, 1915. 

^K.Oswa\.di,Zeitsch.f.exp. Pathol, u. Therapie, 8i 226, 1910; Koll. Zeit. 9, 251 
(1911). 

« M. H. Fischer, (Edema and Nephritis, New York, 1915, pp. 199, 602. 

'E. Bircher, Ergehnisse der Chirwrge u. Orthopcedie, 5, 133 ; Zeits. f. exp., Pathol. 
9. etc. 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 159 

Many of the recognised methods of treating disease are efforts 
made with a view to altering the colloidal state of som^ portion of 
the patient's body, such as the reduction of a swelling by the de- 
hydration of an unduly hydrated gel or varying the amount of dis- 
persion of the colloidal particles in another pai-t of the system. 
Thus, it is now quite recognised that many of the most familiar 
medicines are crude preparations of a colloidal character in which 
the action of the essential ingredient has been largely obscured by 
the presence of adventitious substances, some of which possess un- 
desirable or even toxic properties. The digestive disturbances caused 
by the administration of iron compounds, the headaches which 
accompany the administration of quinine, and the pain resulting 
from the use of silver compounds are well known examples of the 
interference of some subsidiary ingredient of an otherwise useful 
therapeutic agent. 

Many attempts have been made to avoid these complications. In 
some instances, remarkable results have followed the use of extremely 
dilute (i.e., fully ionised) solutions ; other investigators have songht 
to eliminate the disturbing elements and to produce purer medicines, 
and others again have endeavoured to counteract the irritants by 
using two or more drugs in combination. Each of these methods 
has resulted in a certain amount of progress. For many years, how- 
ever, the essentially colloidal character of the recognised remedies 
was overlooked, and the fact was not realised that before a drug can 
exert its full therapeutic action it must be converted into the 
colloidal state. 

One of the earliest to appreciate the importance of using thera- 
peutic agents in a colloidal state was the late Henry Crookes who, 
in 1911, after making protracted experiments, found a means of pro- 
ducing stable prejDarations of colloidal silver, coi)per, iron and 
mercury which were not precipitated by saline solutions. To these 
he gave the name " Collosols." Since that time, stable preparations 
of colloidal solutions of sulphur, iodine and manganese as well as 
those of a much more complex character including some of the 
alkaloids cocaine, etc., have been used extensively by leading medical 
practitioners with wholly satisfactory results. The use of unstable 
colloidal sols has, on the contrary, been far from satisfactory aiul has 
led to serious misconceptions as to the value of remedies in the 
colloidal state. 

Owing to their condition, stable colloidal sols behave in a manner 
quite different from other synthetic medicines. The latter — even 
when dissociated — contains two distinct groups of substances, one 
positive and the other negative. So far as is at present known, a 
diseased organism is deficient in either positive or negative ions, or 
it has an excess of one of these kinds of ion and is unable to get rid 
of it. The former case is much more common than the latter. The 
natural remedy is the presentation of further ions of such a character 
as to make good the deliciency or to remove the excess. If solutions 
of chemical compounds of a crystalline nature are administered they 
must first be dissociated and the requisite ions will then be available 
for use. The action of the ions which are opposite in character to 
those required by the body may be either disadvantageous or neutral, 



160 REPORTS ON THE STATE OF SCIENCE. 1918. 

but as their presence is accidental, if it could be avoided it would 
clearly be to the benefit of the patient. 

By the use of certain colloidal preparations it is possible to 
attain this desideratum and to restore the organism to its normal 
state of ionisation in a relatively simple manner, without the com- 
plexities caused by the presence of unwanted ions. Thus, an 
antemic patient will be assisted by the administration of iron in a 
form in which the amount of haemoglobin in the sy.-^tem can be 
increased, but the administration of excessive doses of an unsuitable 
compound of iron will be useless for this purpose and will be 
detrimental in other ways, such as disturbing the digestive functions. 
The introduction of a soluble salt of iron into the serum will not 
necessarily increase the amount of hfemoglobin, thoui^h the organism 
has a remarkable power of utilising appai-ently unsuitable materials. 
Briefly, it does this by first extracting some of the required agent 
(as when the gastric juices dissolve the ferrous carbonate in a Blaud's 
pill), then, as the solution is usually very dilute, the agent becomes 
dissociated and the required ions are utilised by the organism and 
unnecest-ary ones being eventually discharged. It is obvious, how- 
ever, that if a therapeutic agent is presented in the form in which it 
is required — which in the case of many substances is in the state of 
a colloidal sol — much unnecessary waste of vital energy is avoided, 
the specific action is more direct and efficient, a loss of time which 
must occur before the body has effected the preliminary conversion 
is saved, and troublesome, or even dangerous, side reactions are 
avoided. 

The difference between the action of many medicines and the 
corresiwnding colloidal sols is remarkable. Thus, a 2 per cent, 
solution of iodine in either alcohol or potassium iodide stains the 
skin badly, and when administered internally is very liable to give 
rise to iodism. This is avoided by using a colloidal solution of 
iodine of the same or even greater concentration. 

It is, of course, of the tittnost importance that colloidal medicines 
shall be in a suitable state. Colloidal gels are of value in certain 
cases, but far more important are the colloidal sols. The latter are 
difficult to prepare in a stable form, and unless they are resistant to 
the action of the electrolytes normally present in serum they are use- 
less for therapeutic purposes, as they would be precipitated before 
thej- could eftect the desired purpose. Fortunately, it is easy to test 
the stability of a colloidal sol by examining it under the ultra-micro- 
scope after mixing it with various solutions in respect of which its 
stability may be questioned. 

Colloidal medicines which have not been prepared in a proper 
manner also decompose on long standing. They then show a precipi- 
tate, the amount of which increases as the decomposition continues. 
Properly-prepared, stabilised colloidal sols are quite permanent. 
The writer has kept coUosol iodine and collosol silver for two years 
at a temperature of 70°F., and on examining them under the ultra- 
microscope at the end of this period could observe no difference in 
activity as compared with that of freshly prepared collosol. On the 
other hand, a colloidal silver prepared by Bredig's method was feeble 
after four weeks and inert after seven weeks when kept under the 



I 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 161 

same conditions. The existence o£ the agent in a suitable and 
permanent colloidal state is, therefore, essential. 

In a general sense, sols may be stabilised by preparing them in the 
presence of an emulsoid, such aa gelatin, which appears to surround 
the particles of sol and renders them less sensitive to salt solutions. 
Such protected sols may be evaporated to dryness and the residue — 
which is usually in the form of dark scales — can be brought back into 
a state of colloidal sols by the addition of water. If such " dried 
hydrosols " have been prepared from exceptionally pure materials' 
and with unusual care and skill, they form, when dropped into 
water, colloidal solutions in which the sol has the same properties as 
those previous to evaporation. The present writer has found, how- 
ever, that the commercial " dried hydrosols " which he has examined 
(which are sold under a vai'iety of fancy names) have seldom been pre- 
pared with sufficient skill, and therefore do not yield " solutions " of 
the same power and therapeutic value as can be obtained without 
evaporation ; the advantage of portability gained by the production 
of the dried product is more than counterbalanced by the uncertainty 
as to the strength and activity of the sols produced by adding tap 
water to them in vessels which have not been specially prepared for 
the purpose, and by their instability in the presence of salts. For 
these reasons, he does not favour the use of the di-ied preparations, 
except in cases where it is impossible to use those which have not 
been dried. Moreover, the stability of colloidal sols depends more 
on the mode of preparation than on the presence of a stabilising 
agent. Hence', excellent therapeutic results have been obtained with 
some colloids to which no protective has been added. 

It was realised about ten years ago that colloidal sols of certain 
metals inhibit the growth of all known bacteria, and it has since 
been found that they are harmless to the tissues. For this reason 
the use of colloidal sols has an enormous field of usefulness. They 
can be administered orally or injected in any desired quantities 
without any risk of toxication or undue shock to the system. 

The normal effects of colloidal sols on the blood stream is shown 
by the following experiment" : — 

" A rabbit, weighing 1 kilo., was injected with 2 c.c. of collosol 
hydrargyrum in the auricular vein on the 14th of the month ; on the 
16th of the same month 3 c.c. more were injected. There was no 
local reaction, no bad symptoms ; the rabbit did not go off its food. 
On the 16th it was killed by the usual method, viz., chloroform. 
The arterial system of head and neck were perfused with normal 
saline solution (the eyeballs were very tense). The cerebro-spinal 
fluid was extracted under somewhat increased pressure. A post- 
mortem examination of the rabbit showed no change. A sample of 
the urine was taken, and also a slice of the cerebral cortex, which was 
emulsified and allowed to settle. 

" These three fluids were examined under the ultra-microscope, 
and the observations made were as follows : — 

" The cerebro-spinal fluid showed a distinct cone, with many 
colloidal particles having a strong Brownian movement. 

' H, Crookes, •' Recent Work on Metallic Colloids," Journal of Chemical Terhnologn, 
July, 1915. 

20895 *■ 



162 REPORTS ON THE STATE OF SCIENCE. 1918. 

" The supernatant fluid from emulsion of the brain section showed 
the cone distinctly with occasional colloidal particles. 

" The sediment stirred up with sterile water showed many coarse 
particles and a large number of colloidal particles, many having a 
green colour with strong Brownian movement. 

" The urine showed a strong cone of light, no coarse particles, but 
a very large number of colloidal particles with a strong Brownian 
movement. 

"These results prove that when 'coUosols' are given by intra- 
venous injections they permeate throughout the entire system, and 
that the unutilised or excess portion passes off with the urine." 

The toxicity of colloidal substances depends largely on the 
manner in which they have been prepared and on the presence of 
associated substances. If sufficiently pure and suitably stabilised, 
many of them appear to be wholly non-toxic ; but impure or unstable 
preparations are toxic in proportion to their instability or to the 
adventitious substances present. Colloids such as mercury and 
arsenic, which are not normal constituents of the body cells, are liable 
to be toxic in nerve tissue^ ; but if wholly in the sol state and 
properly sterilised, their toxic power is in^jignificant, and they can be 
injected intravenously or intra-muscularly with impunity, and with 
extraordinarily good results. 

The first effect of injecting a suitable sol into the serum is to 
break up any large protein jjarticles into small ones, thereby increas- 
ing their surface area and activity. After this, the vi^rious colloidal 
materials react, forming the substances required to effect the necessary 
readjustment of the serum and to restore it and the tissues to a state 
of normality. When parasites are present, the protein particles in 
the serum appear to attack them, by some form of surface action, the 
nature of which is not clearly understood though it appears to be 
analogous to the action of staining by aniline dyes. Hence, the 
importance of these protein particles being as sm^all as possible and of 
the metallic colloids in stimulating and accelerating their destructive 
action. 

Expressed in more physico-chemical terms, the blood stream of 
man, like the contents of the cells of all living organisms, is a 
peculiarly sensitive fluid. A slight alteration in the fluids which 
surround it (in adjacent tissues) and even in its own contents brings 
about changes which are so great as to produce illness or even death. 

Lord Lister^" showed that the introduction of septic material into 
the blood gives rise to the developmeiit of large cells or flocculent 
matter which partially decompose with the formation of a thick 
yellow fluid of a highly toxic character. 

Blood serum is, in fact, a typical emulsoid colloid though it is 
characterised by so high a degree of dispersion that it shows the 
Tyndall cone only feebly." Equally significant is Hardy's observa- 
tion^^ that protein is electro-negative in an alkaliue solution and 
electropositive in an acid one. The blood serum in normal health is 

" J. E. R, McDonagh, Urif. Med. Jouvyial, May 19, 1917, p. 618. 

1" Collected Papers (1909), ii. 541. 

" Wiiiterstein, Hand. C. d. vergl. Phys'wlogie 7, 415. 

12 J. Phijxhd., 1899, 24, 288. 



\ 



ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 163 

alkaline, and has a prevailing hydroxy 1 concentration. In many 
diseases this alkalinity is reduced with consequent toxic symptoms. 
To lestore normality it is therefore necessary to reduce the concentra- 
tion of the hydrogen ions or to increase that of the hydroxyl ions. 
The choice between these must depend on other circumstances, and 
especially on the relation of the relative concentrations of the serum 
of the patient in disease and in health. 

An interesting instance of the importance of a knowledge of the 
properties of colloids in the treatment of disease occurs in anaemia. 
In the simplest case this disease is due to a deficiency of iron in the 
hasmoglobin in the blood stream. Haemoglobin is electro-positive, 
and to increase its amount without disturbing the general character- 
istics of the serum, any iron compound administered must also be 
electro-positive when it enters the blood stream. For this reason 
iron carbonate and hydroxide are useful whilst such compounds as 
ferric chloride which are electro-negative and act as coagulants 
should be avoided. The objection to iron carbonate and hydroxide 
lies in the fact that they are usually converted into ferric chloride 
or analogous compounds by the gastric juices and so largely fail to 
reach their destination in a useful form. 

Colloidal iron, on the contrary not being affected by these juices, 
is able to enter the blood stream in a satisfactory and therapeutically 
active form. 

The retention of an unnecessary amount of any substance in the 
blood stream or tissues tends to induce toxicity. The extremely 
minute size of the particles in the colloidal sols is such that they pass 
readily through the tissues and the chances of their being improperly 
stored in the system are correspondingly^^ minimised. In view of 
the foregoing facts it is not surprising that colloids are coming more 
and more to the front in pharmacology^*, particularly those which 
approach the state of true solutions. A good example is seen in 
Fischer's work on oedema^^ in which he has shown that oedema 
results from the imbibition of water by certain colloids. 

The choice of a colloidal sol suitable for a particular pathological 
condition must naturally depend on the cause of that condition. 
This can only be ascertained by trial, though certain broad conclu- 
sions may be reached with respect to the chemical behaviour of 
different substances. In the collodial state, however, many 
substances react entirely differently from what may be regarded as 
their normal behaviour. Thus, colloidal sulphur sometimes acts 
indirectly as an oxidizing agent and both metals and non-metals act 
in a manner which cannot be predicted on general chemical grounds. 

The use of colloidal copper injected intravenously can aggravate 
boils if administered in large doses. In smaller quantities and 
injected intramuscularly, it has the opposite effect, but is far inferior 
to colloidal manganese for this purpose. Indeed, colloidal manganese 

" Sir J. J. Thomson (Eoyal Institution, March, 23rd, 1912) stated that one drop 
of a metallic coUosol contains more than 1,000,000,000,000 particles of metal which 
cannot be detected by ordinary methods and pass readily through the pores of a 
filter. 

i« Porges, Koll. Zeit. 5, 301 (1909). 

>'^ Das Odem ; FAne Expt. v. theor. Unterstiohg, d. Physiologie und PathoUgte 
(1910). 



164 REPORTS ON THE STATE OF SCIENCE. 1918. 

differs from all other remedies in that when it is used for the treat- 
ment of boils it is only very occasionally that fresh boils make their 
appearance during the treatment and these quickly subside without 
further trouble. Colloidal manganese appears to be particularly 
indicated in the treatment of staphylococcic infections. 

Turning now to the specific effects of various colloidal substances* 
it should be noted that the following are all in the sol state and 
that they must (for reasons previously indicated) have been suitably 
stabilised. 

All these colloidal sols are thin fluids containing the colloid in so 
finely suspended a condition that it passes readily through a filter. 

Colloidal silver containing 0*05 percent, of the metal in a colloidal 
form and not as a salt, is a clear, cherry-red liquid which has been 
used by 0. E, A. McLeod with marked success in the following 
cases : — 

By local application on septic and follicular tonsilitis ; Vincent's 
angina ; phlyctenular conjunctivitis ; gonoi'rhceal conjunctivitis ; 
spring catarrh ; impetigo contagiosus, acne of face and body ; septic 
ulcers of legs ; ringworm on body ; tinea versicolor ; soft sores ; 
suppurative appendicitis after operation (the wounds cleaned rapidly) ; 
pustular eczema of scalp and pubes ; chronic eczema of meatus of ear 
with recurrent boils and also chronic eczema of anterior nares ; 
offensive discharge in case of chronic suppuration in otitis media ; 
bromidrosis of feet and axillte ; blind boils on neck. By injection : 
gonorrhoea and chronic cystitis (local), boils, epididymitis. It has 
also been injected intravenously in general blood infections, pneu- 
monia, bronchitis and phthisis in doses of 15-45 minims, with 
marked success. 

Sir James Cantlie has found it particularly effective in cases of 
sprue, dysentery, and intestinal troubles. The dose can be increased 
from one to two or more drachms twice or thrice daily without 
danger. 

A. Legge Roe regards stable colloidal silver as a most useful 
preparation'^ in ophthalmic practice and particularly in cases of 
gonorrhoeal ophthalmia, purulent ophthalmia of infants, infected 
ulcers of the cornea and hypopyon ulcer (tapping of the interior 
chamber and cautery and other operative procedures being now 
rarely required, whilst if perforation does occur it is smaller and 
m.ore manageable), interstitial keratitis, blepharitis, dacryocystitis and 
burns and other wounds of the cornea. 

T. H. Sanderson-Wells used it successfully intravenously in a 
case of^'^ puerperal septicaemia, without any irritation of the kidneys 
and with no pigmentation of the skin. This physician has found 
that a series of intravenous injections each of collosol argentum 
every 48 hours produces no untoward effects and that recovery is 
rapid. 

Sir Malcolm Morris has found that colloidal silver is free from 
the drawbacks of other preparations of silver, viz., the pain caused 

'6 Brit. Med. Journ., Jan. 16, 1915. 
" Lancet, Feb. 16, 1918. 



ON cor.T.oin onEAriSTRY and its industktm. vrrijcvrToxs. Km 

and the discolouration of the skin^* ; instead of producing irritation 
it has, indeed, a distinctlj' soothing effect. It rapidly subdues 
inflammation and promotes the healing of lesions. He has had 
remarkable results in enlarged prostate with irritation of the bladder, 
in prnritis ani and perineal eczema, and in ha-mnrrlioids. It can be 
used in the form of suppositories while a solution is applied to the 
irritated skin. In bromidrosis in the axilla; and feet it'quickly 
gives relief. It causes a rapid disappearance of wans. IJeing non- 
toxic, it can be given internally in urticaria and other forms of 
dermatitis which are suggestive of toxaemia. In such cases it is 
quickly beneficial. 

In ophthalmology, colloid silver has now largely replaced silver 
nitrate as its use is free from pain and its action more direct. 

J. Mark Howell has found colloidal silver beneficial for perma- 
nently'" restoring the potency of the P^ustaohian tubes and for 
reducing nasoi)haryngeal catarrh. 

Colloidal silver has also been used successfully in septic con- 
ditions of the mouth (including pyorrhoea alveolaris — Rigg's disease), 
throat (including tonsilitis and quinsies), ear (including Meniere's 
symptoms and closure to Valsava's inflation) and in generalized 
septicaemia, leucorrhoea, cystitis, whooping cough, and shingles. 
Tests made at King's College show that colloidal silver has an inhibi- 
tive effect on bacteria equivalent to mercuric chloride, but is non- 
toxic, non-irritant and harmless to the host.-"' 

A preparation of colloidal silver which is opaque to X-rays has 
proved invaluable in certain diagnoses. 

Colloidal niercunj. The curiously different action of mercury 
salts according as they are given in small or large doses and in a 
readily or diffictilt soluble form have long puzzled pharmacologists 
It has been generally understood that their action is antiseptic and 
l)actericidal, but according to some of the best known authorities, the 
chief action of mercury is to increase the natural resistance of the 
body to disease. The chief disadvantage of the less soluble mercury 
salts, such as calomel, is their delayed and irregular absorption, with 
subsequent undesirat)le results. The solul)le mercury salts, on the 
contrary, are dangerous on account of their high toxicity. With 
colloidal mercury, the diffusion is extremely rapid and chemical 
afBnity low. Hence the toxicity of colloidal mercury (1 — 2,000) is 
so low that doses of two teaspoonfuls may be taken twice daily or 
intravenous injections of 80 c.c. may be given with impunity. 

Colloidal mercury has cured persistently relapsing malaria in a 
few days.-" 

Some of the colloidal preparations of mercury on the market are 
not suitable for oral administration, but must be injected intramuscu- 
larly. Colloidal mercury is chiefly used in syphilis. 

Colloidal iron, according to Lyn Dimond. killed within six 
minutes, such organisms as bacillus typhosus, bacillus coli 
communis and various pyogenic cocci. The solutions seem to have 

'« Brit. Med. Journ.. May 12, 1917. 

'■■' Brit. Med. Journ.. Dec. If), 1917. 

^^'^LaiuiH (1914), p. 

-" G. Creraoneoe, Gnrr.d. onp. (I'.'lft) 39, <-.'7. 

20g9i G 



166 REPORTS ON THE STATE OF SCIENCE. 1918. 

a definite elective bactericidal action upon such catarrh-causing 
organisms as pneumococcus and various strains of the micrococcus 
catarrhalis. Rapid relief followed the topical application of the 
solution in cases of catarrh of the nose, larynx or pharynx. Colloidal 
iron is also used, by subcutaneous intramuscuiar and intravenous 
injection, in cases of extreme chlorosis, anaemia, erysipelas and 
cellulitis. 

Iron is almost the only metal found in the animal organism which 
is also obtainable in a colloidal state in the presence of water. The 
signihcance of this fact has not yet been sufficiently recognised. In 
the serum, the iron is probably present as a protein compound the 
precise constitution of which has not yet been determined. The 
total iron content of the normal body does not exceed 37 grains, and 
although several organic compounds of iron have been recommended 
they are by no means satisfactory, being either too feeble in action 
or too readily decomposed in corpnre and so rendei-ed useless. 
Inorganic compounds of iron are held by many practitioners to be 
the most efficient in what they consider to be the only true 
test of the value of an iron preparation, i.e., an increase of 
haemoglobin in the blood. The administration of iron in the 
fomn of a colloidal sol appears to be a simple means of increasing 
the amount of the protein compound in the serum, as this form of 
iron, when administered orally, is rapidly diffused in the stomach 
and yet it is not absorbed in individual positions. It is found that 
the amino-acids formed during the process of digestion are readily 
able to absorb into their comjilex molecule a large proportion of the 
iron administered in the colloidal form and from it to effect the 
synthesis of haemoglobin. This is in marked contrast to the behaviom- 
of the carbonate, hydroxide and chloride of iron usually adminis- 
tered. 

Oolluidcd antimony has been used in conjunction with manganese 
with extremely good results in gonococcic infections. In India it has 
given very satisfactory results in Kala-azar, it? administration in this 
disease being accompanied with less risk than that of arsenic. 

Colloidal manganese has been used with remarkable and sur- 
prising results in the treatment of coccogenic skin disease, including 
deep abscesses, boils and deep-seated impetigo. In superficial 
impetigo, chronic seborrhteic eczema and acute folliculitis it is of 
little value when used alone, but gives excellent results when 
employed in conjunction with intramine. The rapidity of its actional 
combined with the saving of dressings render the use of this form 
of manganese very attractive in deep-seated coccogenic lesions. It is 
usually injected inira-muscularly in amounts of 3 c.c. every few 
days. In most cases one injection is sufficient. 

J. E. R. McDonagh-- has also used intravenous injections of 
33 c.c. of colloidal manganese with excellent results in the treatment 
of poisoning by mustaid gas (dichloi'ethyl sulphide) and other oases 
of sulphur poisoning. 

-'J. E. R. McDonagh, Medical Press and f'iiu-Klar, Dec. ;"). 1917; Sir Malcolm 
Morris, Brit. Med. Journ., Apl. 20, 1918 
Medical World (1918), p. 137 



ON COLLOID CHEMISTRY AND ITS INDUSTIIIAI. Al'l'LICATIONS. 167 

Culloidal copper is useful in the treatment of boils, though it is 
inferior to manganese for this i)urpose. In malignant diseases, the 
intra-muscular injection of copper has proved liighly beneficial, the 
metal having been shown to be present in the growth within 24 
hours after injection. Copper is known to have a strong inhibitive 
action on low forms of life. Herschel, de Gres and others have 
stated that colloidal copper exerts an inhibiting action on all cell 
metabolism. In this connexion it is important to note that cases of 
cancel- in which copper can be shown to be present in the growth 
are certainly the ones which are the most amenable to treatment. 
The dilliculty lies in causing tlie copper to penetrate the periphery 
of the cancer. Pessaries of colloidal copper in glVco-geiatiu have 
proved serviceable for uterine fibroids. 

Colloidal arsenic (0-2 %) in doses of 2 c.c. has an extraordinary 
elfect in pernicious amemia and herpes deformans. The simultaneous 
presence of a liquid or colloidal protein ai)pears to be essential to the 
proper reaction ol: ansenic. Thus, sal varsan per .se has no action on the 
spirochfeta pallida, which can move readily for some hours in a 
solution of salvaroan. Yet tlie introduction of a little serum or 
digested protein will cause their immediate death. The elimination 
of ai-senic from the system is usually a matter of difficulty, l)ut in 
the colloidal form its low toxicity combined with the small dosage 
reduce the risk of its jetentiou to a minimum. 

Colloid palladium oxide has been applied successfully in the 
treatment of ol>esity by injecting it hypodermically into the fatty 
areas.--' 

Colloidal jjalladiu in sol has proved of value. in gonori-hea. 
Colloidal nickel lias been used in meningitis. 

Iodine was discovered in IcSil. In the form of an alcoholic solu- 
tion it soon became popular, but was afterwards neglected for manj* 
years. More recently, it has been brought prominently forward and 
at the present time-* it is almost tlie only chemical antiseptic, excej)! 
alcohol, employed by a largf number of British surgeons. 

Colloidal iodine may be obtained in three forms : (i.) aqueous, 
(ii.) oil and (iii.) paste or ointment. The aqueous colloid (1 in 500) 
contains the element in its most active foim, and is suitable for 
administration in all cases in which iodine or an iodide is indicated. 
Its action is more gradual than that of a solution of iodine, but more 
certain than that of iodides, and there is complete avoidance of 
*' iodism " and nausea. '1 he whole of the colloidal iodine is absorbed, 
whereas cSf) per cent, or more of the ordinary iodides administered 
are excreted within 24 hours. 

When injected intravenously, the action of colloidal iodine is 
more rapid, and as much as 300 c.c. has been injected with im- 
punity in cases of pyasmia, and also to effect a softening of fibrous 
tissue, thus showing its absolute nontoxicity. l^er se colloidal 
iodine is only slightly parasitotropic and bacteriotropic, but micrc- 

-'" M. Kauffman, Miiiicb. Mediz. Wochenschr , 525, IOi:{. 
-' Sir R. J. Godlee, Lord Lister (1917), 158. 



168 REl'OKTS ON THE STATE OE SCIENCE. — 1918. 

urgauisuis aiv very greatly iutiueuced by ittj actiuu aud the etfect of 
a subsequently administei-ed remedy is greatly increased. 

Colloidal iodine is also indicated in syphilis by prior injection, 
and also by internal administration, and in cancer by intravenous 
injection. 

In rheumatism, a piece of flannel soaked in colloidal iodine, 
attached to the positive pole of a battery aud applied as near as 
possible to the affected area has been successful. It has also been 
used beneficially as a spray in bronchial and nasal catarrh and 
intei'nally in recovery from alcoholism. 

Colloidal iodine oil (3 per cent.) is very useful for eczema and 
other forms of affections and abnormal conditions of the skin. On 
application, the iodine particles penetrate the pores of the skin with- 
out staining the epidermis, the latter being kept supple and soft by 
the hydrocarbon oil in which the colloidal iodine is exhibited and 
stabilised. Thus, the staining and hardening effects of alcoholic 
and other solutions of iodine are avoided. 

In some cases ^'^ of bad chilblains, colloidal iodine oil was rubbed 
iu four times a day ; every trace of the condition disappeared in 
four days. Equally valuable is this colloid in severe cases of trench 
feet with ulceration and in the many cases of Charcot's bedsores which 
are so troublesome a complication of spinal injuries in military hos- 
pitals. In the earlier inflammatory stages of lupus erythematosus, 
before atrophy has supervened, it is far more suitable than the 
ordinary form of the drug because of the absence of irritation. Simi- 
larly, it is to be preferred for internal administration in the later stage 
of 'syphilis, because there need be no fear of iodism. Parasitic affec- 
tions, again, show a striking amenability to this remedy. In a case of 
dhobie's itch (in which the disease had spread from the groin and 
invaded the trunk, legs and arms) under the quite painless application 
of colloidal iodine oil, the extensive lesions all cleared up in three 
weeks ; with ordinary remedies the case would undoubtedly have been 
more protracted, and the treatment would inevitably have put the 
patient to a good deal of pain. 

Colloidal sulpJiiir (1 per cent.) luis proved invaluable in cases 
where there is a deficiency of this element in the system. The value 
of sulphur has long been known, but the forms in which it is usually 
administered are crude. It has been necessary to employ excessively 
large doses of an insoluble form of sulphur or to administer " Harro- 
gate water" or some equivalent ant" unpleasant prepai-ation of 
hydrogen sulphide. There is little doubt that an insufficient amount 
of available sulphur in tlie system impairs the action of the liver, with 
consequent production of intestinal poisoning (constipation, headache, 
arthritis, etc.). 

Colloidal sulphur is extremely active, readily combines with 
protein and is entirely absorbed in the stomach. The products of this 
combination are rapidly taken into circulation and those parts of the 
(d-ganism foi- which sulphur is necessary are thus supplied. Ordinary 
sulphur is not absorbed in the stomach at all, and passes practically 
unchanged into the intestines. 

" Sir Malcolm Morris, Brit. Med. Juarji., May 12, 11)17. 



ON CiOLl.OlD CilEMlSTRV AM) ITS INDUSXUJAI. A I'l'LlCATlOiNlS. 169 

In many cases of rheumatism and ueurUis aaU evou in "arthritis 
ileformans" reliet: has been rapidly obtained by its internal adminis- 
tration. In acute rheumatism, the intravenous injection of colloidal 
sulphur has proved beneficial. Colloidal sulphur has also been found 
to increase the tolerance to mercury in syphilis when administered 
orally, and has given relief in some cases of cancer when injected 
subcutaneously. 

Colloidal sulphur baths have been of service in rheumatic condi- 
tions and skin affections. Tlis colloidal sulphur content in the bath 
is far greater than that of natural sulphur water, and as the bath 
contains no impurities or free sulphuretted hydrogen it is free from 
the many objections associated with the use uf natural sulphur waters. 

Sir Malcolm Morris has found that among the affections in whicli 
coUoidal^^ sulphur is beneficial are various forms of acne (including 
acne rosacea and seborrhoea), generalised dermatitis, acute i)St)riasis 
and painful fibrositis, whether of connective tissue, of muscle, or of 
joints. Baths medicated with this colloid are, in his experience, at 
once soothing and quickly ctirative. 

(hlloidal alumina (gel)-^ has shown excellent astringent eli'ects 
ill various kinds of diarrhoea and is less toxic than the bismuth 
compounds usually administered in such cases. 

Colloidal qiiininc (sol) appears to be five from the chief disadvan- 
tages of quinine salts, particularly in malaria. The fact that it is not 
so readily lost in the excretions is important as Hartmann and Zila-** 
have found that less than one-third of the quinine salts ordinarily 
administered are retained by the body and that the amount found in 
the blood after oral administration did not exceed 3 per cent, of the 
dose taken. Further investigations are now being made on this 
colloid. 

Production, of Colloidal Remedies. 

The production of colloidal solutions which are sufficiently stiible 
tu be used in medicine is largely a secret, few of the processes 
having been protected by Letters JPatent. No single method either 
of peptisation or stabilisation is suitable for all the variims sols 
re([uired, and as prolonged and costly investigations are i-equired 
before a really stable sol of high therapeutic value can be offered to 
the medical profession it is only natural that the manufacturers 
should keep the information to themselves. The general methods 
by which colloidal sols can be produced and rendered more or less 
stable are well known, and as a still larger number of substances is 
reduced to this state the number of methods used in their produc- 
tion will also increase. Of the methods which have been disclosed, 
the following are the most important, but it should be observed that 
none of these Patent Specifications have been taken out by the 
manufacturers of commercial available colloids used in medicine in 
this country and that they do not describe the methods used in 
producing the highly stable colloids which have yielded the results 
mentioned in the present report : — 

No. 12,037/1911. F. Arledter, Preparation of sols. 

No. 1219/1912. A. Bering, Preparation of Colloidal Mercury. 

■^6 Ihid. 

" Eng. Pat. 101, GOi). 

^'^ Arch. f. cxper. Path. u. Phannakol. I'JIS, 83> --1- 



170 ' REPORTS ON THE STATE OF SCIENCE. — 1918. 

No. 11,771/1912. E. Fodszus, Preparation of sols. 

No. 14,235/1912. B. Schwerin, Preparation of sols. 

No. 29,049/1912. Ges. f. Elektro-Osmose, Preparation of sols. 

No. 7238/1913. Aktiebol : KoUoicl Preparation of Colloidal 
Sulphur. 

No. 9237/1914. Ges. f. Elektro-Osmose, Preparation of Colloidal 
Silica. 

No. 9261/1914. Ges. f. Elektro-Osmose, Preparation of Metal sols 
with silica. 

No. 15,267/1914. Ges. f. Elektro-Osmose, Preparation of Metal sols. 

No. 15,127/1915. Soc. Chem. Ind. Basle, Preparation of Colloidal 
Copper. 

No. 104,609 (1917). Monneron & Guye, Preparation of Colloidal 
Alumina erel. 

Colloids and Synthetic Compounds. 

There is no necessary incompatibility between colloidal sols and 
synthetic compounds which are not regarded as being in the colloidal 
state. Each of these groups of remedies has its own sphere of 
usefulness, and some of the synthetic drugs are more colloidal than 
is generally supposed (see section on Dyes in the 1917 B. A. Report 
on Colloids). In view, however, of the large amount of work which 
has been done by Ehrlich and others in the preparation of synthetic 
compounds of arsenic and other metalloids it appears desirable to 
draw attention to the following facts : — 

The action of synthetic compounds is usually due to their high 
molecular weight and often to the presence of ortho-amino groups. 
In some cases, a metal or metalloid is separated in colloidal sol 
foi'm in the blood, the remainder of the drug merely serving as a 
vehicle. In others, the whole compound acts as a reducing or 
oxidizing agent. It may or may not ]je a coincidence that the most 
effective therapeutic reducing agents contain a metalloid (such as 
sulphur or iodine) whilst the most effective oxidizing agents contain 
a metal. 

In this connexion it is jjarticularly interesting to compare the 
almost non-toxic colloidal metals and metalloids with that of the 
well known salvarsans and their compounds containing phosphorus 
(galyl), platinum, gold, copper or silver. According to Kolle^^ the 
following doses are toxic to syphilitic rabbits ; smaller doses are 
toxic to the human subject : — 

ToxU 

Salvarsau 

Neo-Salvaisau ... 

Hexamino-Salvarsau ... 

tialyl 

Bismethyl-Staudaid 

Dichlorarsalyte ... 

Dibroinarsalyte ... 

Diiodaisalyte 

(loppcr Salvarsau K;, 

Platinum Salvarsan 

Gold Salvarf?an 

Silver Salvarsau 

" Deutsche Med.-Wochensclir. 1918, 44, 11 1 ,.11727 



Doise i/niig. 


Toler 


(tied Dose grins. 


')-125 ' 




0-1 


0-25 -0-3 




0-2 


— 




0-1.5 


0-12.5 




0-1 


0-2f> 




0-22 


0-2.5 




0-2 


0-36 




0-3 (?) 


(J-U4 




( i-oar. . 


0-07 




0-0."i 


0-O.S 




0-02 


ti-H 




o-i2r) 



ON coij.niD <iiF.\rrsri!v and its industki \i, ai'pmcation.s. 171 

It is well known that most of these salvarsan conipoimtlK 
leterioratt' aiul become more toxu; on exposure to air. Thus within 
an hour the toxicity of iieo-salvaraan increases i\ to (i toltl, tht- 
arsalj'tes within 24 hours increase 2.} times in toxicity, and the same 
applies to the metallic salvarsan compounds. Colloidal metal sols 
do not become toxic, even on prolonged exposure. 

Hexamino-salvarsan in the moderate dose of O'l grm. has pro- 
duced grave symptoms and even fatal results which led to its 
discontinuance. Gold and platinum salvarsan possess too great a 
toxicity for therapeutic use in man. Silver salvarsan, on the 
contrary, is 2 to o times as potent as old salvarsan and it is by far the 
most active form of salvarsan for destroying the spiroch;Btes in 
rabbit syphilis and in curing the lesions. It has likewise been used 
with excellent results in man in doses of ()'2 to 0*4 grm. Kolle does 
not state the exact chemical constitution of this substance, but it is 
highly probable that much of the silver is in a colloidal state, 
especially as he found that colloidal silver (coUargol) alone in doses 
of O'OH grms. per kilo caused the rapid disappearance of spirocha^tes 
in the rabbit. 

Colloids and Physiological Extracts. 

The remarkable results which haA'e followed (he administration 
of certain physiological extracts (thyroid, pituitary, etc.) appear 
to be largely due to the presence, in them, of sulphur oi- jm 
equivalent element in a suitable form. 

The substitution of carefully prepared colloidal sols for such 
extracts largely avoids the risks of irregular and uncertain com- 
jjosition which inevitably accompany the use of such extracts. 

OoUoids in Veferitiari/ Practice. 

Colloidal silver and sulphur have yielded excellent results in 
veterinary practice, the former in the treatment of swellings, sprains, 
bruises, wounds, sores, rheumatism, thrush in the feet, fistula, various 
skin diseases and inflammation of the eyes, and the latter for cases 
where a deficiency of sulphur is indicated. 

The Limitations of Colloids. 

The selection and use of colloidal sols requires the same care and 
skill as the administration of any other remedies, but with the great 
advantage of being made specific and rational rather tha?i empiric. 

A word of warning may be expressed as to the use of unstalile 
colloids in medicine. A number of colloidal preparations — particu- 
larly of silver and iodine — has been placed on the market which 
have not been properly stabilised. The use of these preparations 
has been accompanied by disap])ointing results, as it is essential (as 
previously mentioned) that the colloids exhibited should be stable 
in the presence of serum and saline solutions. 

The failure of numerous colloidal sols of German (and some of 
British) origin created, in some minds, a prejudice against all colloidal 
remedies. The failures have been found, in every case examined, to 
have been wholly due to the method of preparation. Thus, it has 



172 I?EPOT?TS ON THE STATE OF SCIENCE. 

been fomid that Colloidal mfetals uvepared by Bredig's method (die- 
persiou by an electric arc with poles of the desired metal) are 
unsuitable for medicinal purposes, as they are not only unstable 
in themselves, but are rapidly decomposed by electrolytes present in 
rbe human organism. Where properly stabilised colloidal sols are 
employed they are as reliable as any of the preparations in the 
Pharmacopoeia. 

It should be observed that some so-called synthetic remedies are 
found to be colloidal sols, though this is not generally known. This 
has led to some curious misstatements in regard to the relative 
therapeutic values of colloids and synthetic drugs. 

Owing to the impossibility of repressing ail side reactions in 
making experiments on the living subject, pharmacology and 
chemotherapy are among the most inexact of sciences. Yet the 
success which has attended investigations on the use of colloids as 
remedial agents is so great as to call for the sympathetic interest of 
all who can appreciate what has been accomplished, and affords a 
basis of hope that further developments will be still more beneficial 
to suffei'ing humanity. It is highly probable that serum and vaccine 
therapy will ultimately be resolved into questions of colloidal 
chemistry, but in the meantime the use of colloidal solutions of 
certain elements appeal's to offer a means whereby the various 
colloids can be accurately prepared and administered with a higher 
degree of efficiency than is possible with some of the more complex 
synthetic compounds at present in use. 

The ever-increasing use of colloidal sols in military and private 
practice is a certain indication of their value, and among the indirect 
results of the Woi'ld War, the facilities which it has given for the 
investigation of many hitherto obscure problems of disease and the 
opportunities which it has afforded for ascertaining the value and 
rationale of many new remedies, will be among the blessings of a 
catastrophe which is, otherwise, too awful to contemplate. 

Literature. 

The literature on the applications of colloid chemistry to biology 
and physiology,'^" and in the "' Kolloidchemie Beihefte," " Kolloid 
Zeitschrif r," and " Biochemische Zeitschrift " should be consulted. 

Papers on the application of colloids in therapeutics also appear 
frequently in the " British Medical Journal," '' The Practitioner," 
"• The Lancet," and various foreign medical journals. Notwithstand- 
ing the voluminous literature on the general subject a vast amount 
of research into details remains unexplored. In the prosecution of 
further work, it is well to recall the words of a former president to 
the effect that " Medicine is no unworthy ally of the British Associa- 
tion and while her practice is ever more and more based on Science, 
the ceaseless efforts of her votaries are ever largely adding to the sum 
of abstract knowledge. ""^ 

■■"' See "First Report on Colloidal Chemistry," British Association, 1917. pp. S."), St;. 
Also present Report, pp. 117-154. 

•^' Sir J. Lister, '• Interdependence of Science and the Healing Art." Presidential 
address to Brit. Assn., 1896^ 



VT^r^ 3SEP..919 



BEITISH ASSOCIATION FOR THE ADVANCEMENT 

OF SCIENCE. 



PUBLICATIONS ON SALE AT THE OFFICE OF THE ASSOCIATION 
BuRUNQTON House, Piccadillt, London, W. 1. 

Life Members (since 1845), and all Annual Members who have not intermitted their 
subscriptions, receive gratis all Reports (Annual Volumes) published after the 
date of their membership. 

Associates for any Meeting may obtain the Annual Volume relating to that Meeting 
at two-thirds of the publication price. 



The price of any Annual Volume, for the years 1831-1876 inclusive, will be quoted on 

application to the Office of the Association. 
A few sets, from 1831 to 1874 inclusive, are available at £10 per set. 
The publication price of each Annual Volume since 1877 is £1 4a. 
The President's Address, and Sectional Addressee, bound together, for 1888, 1889. 

1890, 1891, 1892, 1893, 1895, 1896, 1899, 1900, 1901, 1902, 1909, 1910 (paper), 

each U., 1913, 1914, 1915 {doth), 2s. 
Addresses by the Presidents of the Association are obtainable {separately) for several 

years after 1860, each 3d. 
Many of the Sectional Presidents' Addresses are obtainable separately for years since 

1864, each 3d. 

Lithographed Signatures of the Members who met at Cambridge in 1833, with the 

Ih-oceedings of the Public Meetings, 4to, 4^. 
Index to the Reports, 1831-1860, 12s. (carriage included). 
Index to the Reports, 1861-1890, 15s. (carriage, 6d.). 



Lalande's Catalogue of Stais, £1 Is. 

Stellar Distribution and Movements, by A. S. Eddington, M.Sc, 1911, 3d. 

Report of the International Conference on Terrestrial Magnetism and Atmospheric 

Electricity, 1898, 6d. 
Preliminary Report on the Magnetic Survey of South Africa, 1906, 3d. 
Report on Seismology, 1900, Is. ; 1901, Is. ; 1902, Is. ; 1904, Is. ; 1905, Is. ; lOOG, 

6d. ; 1907, 6d. ; 1908, Is. ; 1909, Is. ; 1910, Is. ; 1911, Is. ; 1912, Is. ; 1913, 

Is.; 1914, Is.; 1915, Is.: 1916, Is.: 1917, Is. 
Catalogue of Destructive Earthquakes, a.d. 7 to a.d. 1899, by Dr. J. Milne, F.R.S., 

1912, 5s. 



Report of the Committee for constructing and issuing Practical Standards for use in 

Electrical Measurements, 1892, 6i. ; 1893, 6d. ; 1894,1s.; 1895, 6d. ; 1899, 6rf. ; 

1903, Qd. ; 1904, 6d. ; 1905, 6d. ; 1906, 6d. ; 1907, 6rf. ; 1908, 6rf. ; 1909, 3d. 

(The complete Reports of this Committee have been reprinted, demy 8vo., 

12». Cid., Cambridge University Press.) 
The Action of Magnetism on Light, by J. Larmor, F.R.S., 1893, Is. 

20895 " 



2 

Report on the Present State of our Knowledge of Thermodynamics, Part II., by 
G. H. Bryan ; with an Appendix by Prof. L. Boltzmann, 1894, Is. 

Report on the Comparison of Magnetic Instruments, 1896, 4:d. 

Report on the Bibliography of Spectroscopy in continuation of 1894 Report, 1898, 
Is. 6d. ; 1901, Is. 6d. 

Note sur I'Unite de Pression, par le Dr. C. E. Guillaume, 1901, 3d. 

Note on the Variation of the Specific Heat of Water, by Prof. H. L. Callendar, 1901, 4d. 

On Threefold Emission Spectra of Solid Aromatic Compounds, by Prof. E. Goldstein, 
1909, 3d. 

Anode Rays and their Spectra, by Dr. Otto Reichenheim, 1909, 3d. 

The Principle of Relativity, by E. Cunningham, 1911, 3d. 

Report on the Determination of Gravity at Sea, 1916, Is. 



Report on Tables of the Bessel Functions, 1896, Is. 

Tables of F (r, v) and H (r, v) Functions, 1899, Is. 

The History and Present State of the Theory of Integral Equations, by H. Bateman, 

1910, Is. Qd. 
Report on the Calculation of Mathematical Tables, 1916, Is. 



Report on Electrolysis, 1886, Is. ; 1887, 6-^. ; 1888, 6d. 

Report on the Present State of our Knowledge of Electrolysis and Electro-chemistry, 

1893, 6d. 
Discussion on the Theory of Solution, 1890, 6d. 



Report on Wave-lengths, 1899, Is. ; 1900, with Index to Tables from 1884 to 1900, 

Is. ; 1901, Is. 
Report on the Chemical Compounds contained in Alloys, by F. H. Neville, F.R.S., 

1900, 6d. 

The Constitution of Camphor, by A. Lap worth, D.Sc, 1900, Is. 

Report on Absorption Spectra and Chemical Constitution of Organic Substances, 

1901, Is. 

The Relative Progress of the Coal-tar Industry in England and Germany during the 

past Fifteen Years, by Arthur G. Green, 1901, Gd. 
The Methods for the Determination of Hydrolytic Dissociation of Salt Solutions, by 

R. C. Farmer, 1901, Qd. 
The Application of the Equilibrium Law to the Separation of Crystals from Complex 

Solutions and to the Formation of Oceanic Salt Deposits, by Dr. E. Frankland 

Armstrong, 1901, Is. 
Our Present Knowledge of Aromatic Diazo-compounds, by Dr. Gilbert Thomas Morgan, 

1902, 6d. 

The Present Position of the Chemistry of Rubber, by S. S. Pickles, 1906, 6d. 

The Present Position of the Chemistry of Gums, by H. Robinson, 1906, 3d. 

The Sensitiveness of Indicators, by H. T. Tizard, 1911, 3d. 

Diffusion in SoUds, by Dr. C. H. Desch, 1912, 3d. 

SolubUity, by J. Vargas Eyre, Ph.D. Part I., 1910, Is. ; Part II., 1913, Is. 

Report on the Absorption Spectra and Chemical Constitution of Organic Compounds, 

1916, Is. 
First Report on Colloid Chemistry and its Industrial Applications, 1917, 2s. [The 

Second Report is on sale at H.M. Stationery Office, price Is. 6ri.J 



Report on the Character of the High-level Shell-bearing Deposits at Clava, ChapelhaU, 

and other Localities, 1893, 6d. 
Fourth Report on the Erosion of the Sea Coast of England and Wales, 1895, 9d. 



Report on the Changes in the Sea Cbast, 1903, Is. 

Report on the Structure of Crystals, 1901, Is. 

Report on Ldfe-zonea in the British Carboniferous Rocks, 1901, Grf. ; 1902, 6d. 

The Formation of * Rostro-Carinate ' Flints, by Professor W. J. Sollas, F.R.S., 1913, 3d. 

Missing Links among Extinct Animals, by Dr. A. Smith Woodward, 1913, 3d. 



Rules of Zoological Nomenclature, la. 

Digest of Observations on the Migration of Birds, made at Lighthouses, by W. Eagle 

aarke, 1896, Gd. 
Report on the Migratory Habits of the Song- thrush and the White Wagtail, by W. 

Eagle Clarke, 1900, 6d. 
Report on the Migratory Habits of the Skylark and the Swallow, by W. Eagle Clarke 

1901, 6d. 

Report on the Migratory Habits of the Fieldfare and the Lapwing, by W. Eagle Clarke , 

1902, 6d. 

Report on the Migratory Habits of the Fieldfare and the Lapwing, by W. Eagle Clarke, 

1903, dd. 

Melanism in Yorkshire Lepidoptera, by G. T. Porritt, 1906, 6d. 

Report on the Biological Problems incidental to the Belmullet Whaling Station, 1912, 

3d. ; 1914, Is. 
On the Phylogeny of the Carapace, and on the Affinities of the Leathery Turtle, 

Dermochdys coriacea, by Dr. J. Versluys, 1913, 6d. 



On the Regulation of Wages by means of Lists in the Cotton Industry : — Spinnmg, 
2s. ; Weaving, is. 

Report on Future Dealings in Raw Produce, 1900, 6rf. 

Report on Women's Labour, 1903, 6d. 

Report on the Accuracy and Comparability of British and Foreign Statistics of Inter- 
national Trade, 1904, 6d. 

Report on the Amount and Distribution of Income (other than Wages) below the 
Income-tax Exemption Limit in the United Kingdom, 1910, 6d. 

Report on the Effects of the War on Credit, Currency, and Finance, 1915, (id. 

Report on the Question of Fatigue from the Economic Standpoint, 1915, 6rf. ; li>lG, Crf. 



Second Report on the Development of Graphic Methods in Mechanical Science, 1892, Is. 

Report on Planimeters, by Prof. 0. Henrici, F.R.S., 1894, Is. 

Second Report on a Gauge for Small Screws, 1884, reprinted 1895, Gd. 

Report on giving practical efifect to the Introduction of the British As.sociation Screw- 
Gauge, 1896, 6d. ; 1901, 6d. ; 1903, 6d. 

Report on Proposed Modification of the Thread of the B.A. Screw, 1900, (id. 

Report on the Resistance of Road Vehicles to Traction, 1901, 3d. 

The Road Problem, by Sir J. H. A. Macdonald, 1912, 3d. 

Standardisation in British Engineering Practice, by Sir John Wolfe-Barry, K.C.B.. 
1906, 3d. 

Report on the Investigation of Gaseous Explosions, with special reference to Tem- 
perature, 1909, 6d. ; 1914, 6d. 

Gaseous Combustion, by William Arthur Bone, D.Sc, F.R.S., 1910, 6d. 

The Present Position of Electric Steel Melting, by Professor A. Mc William, 1911, 3rf. 



DiscuBsion on the Proper Utilisation of Coal, and Fuels derived therefrom, 1913, Qd. 
Liquid, Solid, and Gaseous Fuels for Power Production, by Professor F. W. Burstall 
1913, Sd. 

Repoit on the Standardisation of Impact Tests, 1918, 9fZ. 



Report on Anthropometric Investigation in the British Isles, 1906, Is. ; 1907, 3d. 
Fifth to Twelfth Reports on the North- Western Tribes of Canada, 1889, Is. ; 1890, 
2s. 6d. ; 1891, Is. ; 1892, Is. ; 1894, 6d. ; 1895, Is. 6d. ; 1896, 6d. ; 1898, Is. Qd. 
Report on the Ethnological Survey of Canada, 1899, Is. 6d. ; 1900, Is. 6d. 
Report on Artificial Islands in the Lochs of the Highlands of Scotland, 1912, M. 
Report on the Archaeological and Ethnological Researches in Crete, 1910, &d. ; 1912, 6d. 
Report on Physical Characters of the Ancient Egyptians, 1914, 6d. 



The Claim of Sir Charles BeU to the Discovery of Motor and Sensory Nerve Channels 
(an Examination of the Original Documents of 1811-1830), by Dr. A. D. Waller, 
F.R.S., 1911, Gd. 

Heat Coagulation of Proteins, by Dr. Chick and Dr. Martin, 1911, Zd. 



Second Report on the present Methods of Teaching Chemistry, 1889, 6d. 

The Influence of the Universities on School Education, by the Right Rev. John 
Percival, D.D., Lord Bishop of Hereford, 1901, 3d. 

Report on the Curricula of Secondary Schools, 1907, 3d. 

Report on Mental and Physical Factors involved in Education, 1910,3c?. ; 1911, 3d. ; 
1912, 3d. 

Report on the best means for promoting Scientific Education in Schools, 1867, 6d. 

Report on the Sequence of Studies in the Science Section of the Curriculum of Secondary 
Schools, 1908, 3d. 

Report on the Teaching of Elementary Mathematics, 1902, 3d, 

Report on the Teaching of Botany in Schools, 1903, 3d. 

Report on the Position of Geography in the Educational System of the Country, 1897, 
6d. 

Report on Geographical Teaching in Scotland, 1913, 3d. 

Interim Report on the Popularisation of Science through Public Lectures, 1916, Gd. 

Report on Science Teaching in Secondary Schools, 1917, 2s. 

Report on the Influence of School Books upon Eyesight, 1913 (Second Edition 
revised), id. 

Report on the number, distribution, and respective values of Scholarships, Exhibi- 
tions, and Bursaries held by University students during their undergraduate 
course, and on funds private and open available for their augmentation, 1913, id. 



Discussion on Agriculture and Science, Ipswich, 1895, 3d. 

The Development of Wheat Culture in North America, by Professor A. P. Brigham, 
1909, 3d. 

A number of shorter Reports, etc., for recent years, in addition to the above, are also 
available in separate form ; inquiries should be addressed to the office. 



SEP.i919